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Local Area Networks – The Basics
Learning Objectives
After reading this chapter you should be able to:
• State the definition of a local area network.
• List the primary function, activities, and application areas of a local area network.
• Cite the advantages and disadvantages of local area networks.
• Identify the physical and logical local area networks.
• Specify the different medium access control techniques.
• Recognize the different IEEE 802 frame formats.
• Describe the common wired local area network systems.
Chapter Outline
1. Introduction
2. Primary Function of Local Area Networks
3. Advantages and Disadvantages of Local Area Networks
4. The First Local Area Network – The Bus/Tree
5. A More Modern LAN
a. Contention-based protocols
6. Switches
a. Isolating traffic patterns and providing multiple access
b. Full-duplex switches
c. Virtual LANs
d. Link aggregation
e. Spanning tree algorithm
f. Quality of service
7. Wired Ethernet
8. Wired Ethernet Frame Format
Chapter 7

9. LANs In Action: A Small Office Solution
10. Summary
Lecture Notes
Introduction
A local area network (LAN) is a communication network that interconnects a variety of data
communicating devices within a small geographic area and broadcasts data at high data transfer
rates with very low error rates. Since the local area network first appeared in the 1970s, its use
has become widespread in commercial and academic environments. It would be very difficult to
imagine a collection of personal computers within a computing environment that does not
employ some form of local area network. This chapter begins by discussing the basic layouts or
topologies of the most commonly found local area networks, followed by the medium access
control protocols that allow a workstation to transmit data on the network. We will then examine
most of the common Ethernet products.
Functions of a Local Area Network
The majority of users expect a local area network to perform the following functions and provide
the following applications: file serving, database and application serving, print serving,
electronic mail, remote links, video transfers, process control and monitoring, and distributed
processing.
Advantages and Disadvantages of Local Area Networks
Local area networks have several advantages, including hardware and software sharing,
workstation survival during network failure, component and system evolution, heterogeneous
mix of hardware and software, and access to other LANs, WANs, and mainframe computers.
Disadvantages include complexity, maintenance costs, and the network is only as strong as the
weakest link.
The First Local Area Network – The Bus/Tree
The bus local area network was the first physical design when LANs became commercially
available in the late 1970s, and it essentially consists of a single cable, or bus, to which all
devices attach. Since then the bus has diminished significantly to the point of near extinction. It

is interesting to note that cable television signals are still delivered by a network bus. Thus,
understanding the bus/tee network is still important.
A More Modern LAN
The most popular configuration for a local area network is the star-wired bus. This form of LAN
should not be confused with an older technology called the star topology. Today’s modern star-
wired bus network acts like a bus but looks like a star. The logical design of operates as a bus
where one workstation can transmit to all other workstations. The physical design, however,
more resembles a star, with the hub or switch acting as the central point.
Contention-based Protocols
A medium access control protocol is part of the software that allows a workstation to place data
onto a local area network. Depending on the network’s topology, several types of protocols may
be applicable. The bottom line with all medium access control protocols is this: Since a local
area network is a broadcast network, it is imperative that only one workstation at a time be
allowed to transmit its data onto the network. In the case of a broadband local area network,
which can support multiple channels at the same time, it is imperative that only one workstation
at a time be allowed to transmit its data onto a channel on the network. There remains only one
basic category of medium access control protocol for local area networks: contention-based.
Switches
A switch is a combination of a hub and a bridge and can interconnect multiple workstations like
a hub but can also filter out frames providing a segmentation of the network. Switches can
provide a significant decrease in interconnection traffic and increase the throughput of the
interconnected networks while requiring no additional cabling or rearranging of the network
devices. Modern switches can provide full-duplex connections, virtual LANs, aggregated links,
support spanning tree algorithms, and provide quality of service levels.
Wired Ethernet
The various versions of wired Ethernet include the older 10 Mbps systems, 100 Mbps, Gigabit,
and 10 Gbps.
Wired Ethernet Frame Format
The IEEE 802 set of standards has split the data link layer into two sublayers: the medium access
control sublayer and the logical link control sublayer. The medium access control (MAC)
sublayer works more closely with the physical layer and contains a header, computer (physical)
addresses, error detection codes, and control information. The logical link control (LLC)
sublayer is primarily responsible for logical addressing and providing error control and flow
control information.

LANs In Action: A Small Office Solution
The first In Action example examines how a small business decides to incorporate a LAN into
their business solution. The business included 35 - 40 workstations with word processing,
spreadsheets, and database applications. In order to add internal e-mail, a central database
system, and print sharing, the company will consider the addition of a local area network.
Quick Quiz
1. What are the major functions of a LAN?
File and print serving, access to other LANs, WANs and mainframes, distributed processing, and
process control.
2. What are the various medium access control techniques?
Contention-based. Round robin systems have essentially disappeared.
3. What is the difference between a hub, a switch, and a router?
Hub broadcasts any input onto all outgoing lines; switch replaces a hub and provides filtering;
router interconnects a LAN with a WAN.
4. What are the basic functions of a network server?
Holds network operating system as well as application programs and data set; may also function
as a hub, switch, bridge or router.
Discussion Topics
1. Couldn’t IEEE have made a single frame format for all the forms of local area networks?
2. Are LANs a stable technology or are they changing just as quickly as other forms of
communication technologies?
3. Is Ethernet that good that it’s the predominant form of LAN? Will everything eventually be
Ethernet / CSMA/CD?
4. Will hubs be obsolete someday?
5. What are the advantages of creating virtual LANs?

Teaching Tips
1. Be sure to emphasize the difference between logical view and physical view. For example, a
star-wired bus logically acts like a bus but physically looks like a star. A star-wire ring logically
acts like a ring but physically looks like a star. A bus logically and physically is a bus.
2. The frame is the name of the package at the data link layer. It is the frame that is placed onto
the medium of the physical layer. The IEEE 802 frame formats describe the layout of the frame
and what the data looks like as it moves over a LAN. The frame addresses are the ones used to
address a NIC in a machine. This is not the address that is used to send a packet over the Internet
(that is the IP address).
3. Discuss the non-determinism of the CSMA/CD LAN and how collisions in hub-based LANs
create this characteristic. Discuss how switches and no collisions have changed things.
4. What kind of mix does your school or company have of hubs, routers, and switches? Use this
information as an example in class.
5. Take your students to one or more locations on campus and show them an actual, working hub
/ switch / router.
6. Make sure you emphasize how a switch filters out unnecessary packets.
Solutions to Review Questions
1. What is the definition of a local area network?
A communication network that interconnects a variety of data communicating devices within a
small geographic area and broadcasts data at high data transfer rates with very low error rates.
2. List the primary activities and application areas of a local area network.
File serving, print serving, connection to other networks and mainframes.
3. List the advantages and disadvantages of local area networks.
Adv: Share files and devices, intercommunication.
Disadv: Maintenance, complexity, costs.
4. What are the basic layouts of local area networks? List two advantages that each layout
has over the others.
Bus: Uses low noise coaxial cable, inexpensive taps.
Star-wired bus: Simple to interconnect, easy to add components, most popular.

Star-wired ring: Simple to interconnect and easy to add components (but no more so than star-
wired bus).
5. What is meant by a passive device?
A signal that enters is neither amplified nor regenerated. The signal is simply passed on.
6. What is meant by a bidirectional signal?
A signal that propagates in either direction on a medium.
7. What are the primary differences between baseband technology and broadband
technology?
Baseband is a signal digital signal while broadband is analog and may carry many signals.
8. What purpose does a hub serve?
The hub is a collection point for workstations.
9. What is the difference between a physical design and a logical design?
Physical is the wiring and components, logical is how the software passes the data.
10. What is a medium access control protocol?
The software that allows a workstation to insert its data onto the LAN.
11. What are the basic operating principles behind CSMA/CD?
CSMA/CD: Listen to medium, if no one transmitting, transmit. Continue to listen for collisions.
If someone is transmitting, wait.
12. What is meant by a “nondeterministic” protocol?
You cannot determine precisely when a workstation will get a chance to transmit (because of
potential collisions).
13. What does the term 100BaseT stand for?
One hundred mega-bits per second transmission over baseband (digital) signals, using twisted
pair wiring.
14. What is the difference between Fast Ethernet and regular Ethernet?
Fast Ethernet transmits at 100 Mbps while regular Ethernet transmits at 10 Mbps.

15. What are the latest 10-Gbps Ethernet standards?
10GBase-fiber, 10GBase-T, 10GBase-CS
16. What is the primary advantage of power over Ethernet? The primary disadvantage?
Primary advantage is not having to run a separate power line to power device; primary
disadvantage is making sure the switch has enough power to run PoE devices.
17. How does a transparent switch work?
Observes traffic on a LAN and creates a set of forwarding tables; filters traffic
18. What is the purpose of a virtual LAN?
To create a logical subgroup of multiple workstations and servers.
19. How does a switch encapsulate a message for transmission?
It really doesn’t encapsulate anything. Switch looks at NIC/MAC addresses and forwards
accordingly.
20. When referring to a hub or a switch, what is a port?
The port is the connection that is used to connect a workstation or another hub or switch to this
hub or switch.
21. What are the basic functions of a switch?
A switch examines a packet’s destination address and routes the packet to the appropriate
workstation.
22. How does a switch differ from a hub?
Switch examines addresses, hub does not. A switch has multiple ports and takes the place of a
hub.
23. What is cut-through architecture?
The device is passing the data packet on before it has even finished entering the device.
24. How is a full-duplex switch different from a switch?
Full duplex switch has one set of lines for receiving and one set of lines for transmitting, thus it
can do both operations at the same time.

25. What is meant by link aggregation?
The process of combining two or more links into one logical fat link.
Suggested Solutions to Exercises
1. What properties set a local area network apart from other forms of networks?
Small geographic distances using broadband transmissions.
2. Describe an example of a broadband bus system.
Cable modems, video surveillance systems, cable television.
3. Is a hub a passive device? Explain.
Not completely. A hub does regenerate a digital signal. And there may be some simple network
management functions performed in a hub.
4. Which of the Ethernet standards (10 Mbps, 100 Mbps, 1000 Mbps, 10 Gbps) allow for
twisted pair media? What are the corresponding IEEE standard names?
Currently all but 10 Gbps Ethernet can run over twisted pair.
5. If a network were described as 1000BaseT, list everything you know about that network.
CSMA/CD LAN, 1000 Mbps transmission, baseband or digital signaling, twisted pair wiring.
6. In the IEEE 802.3 frame forma, what is the PAD field used for? What is the minimum
packet size?
PAD field makes sure the frame is not mis-interpreted as a runt. Minimum packet size is 64
bytes.
7. Suppose workstation A wants to send the message HELLO to workstation B. Both
workstations are on an IEEE 802.3 local area network. Workstation A has the binary
address “1" and workstation B has the binary address “10." Show the resulting MAC
sublayer frame (in binary) that is transmitted. Don’t calculate a CRC; just make one up.
HEADER 10 1 5(data length) HELLO PAD(33 bytes) CHECKSUM
8. What is the difference between the physical representation of a star-wired ring LAN and
the logical representation?

A star-wired ring LAN physically looks like a star but acts logically like a ring. A star-wired bus
physically looks like a star but acts logically like a bus.
9. How is a hub similar to a switch? How are they different?
Not too much similar. They both physically connect into the network the same. Both forward
frames. But a switch looks at the MAC address and either forwards or drops the frame.
10. Are hubs and switches interchangeable? Explain.
Yes. But results can be quite different.
11. a. The local area network shown in Figure 7-21 has two hubs (X and Y) interconnecting
the workstations and servers. What workstations and servers will receive a copy of a
packet if the following workstations/servers transmit a message:
• Workstation 1 sends a message to workstation 3:
• Workstation 2 sends a message to Server 1:
• Server 1 sends a message to workstation 3:
All devices will receive all messages.
b. Replace hub Y with a switch. Now what workstations and servers will receive a copy of a
packet if the following workstations/servers transmit a message:
• Workstation 1 sends a message to workstation 3:
• Workstation 2 sends a message to Server 1:
• Server 1 sends a message to workstation 3:
Workstations 1, 2 and 3.
Workstations 1, 2 and the server.
Only workstation 3.
12. A transparent switch is inserted between two local area networks ABC and XYZ.
Network ABC has workstations 1, 2 and 3, and network XYZ has workstations 4, 5, and 6.
Show the contents of the two forwarding tables in the switch as the following packets are
transmitted. Both forwarding tables start off empty.
• Workstation 2 sends a packet to workstation 3.

At the end:
Routing table on ABC’s port: 1, 2
Routing table on XYZ’s port: 4,5,6
13. Give an example of a situation in which a virtual LAN might be a useful tool in a
business environment. What about in an educational environment?
If you want a certain group of users to work together on a project, you might want to place them
on a virtual LAN. Likewise for school.
14. What does it mean when a switch or device is cut-through? What is the main
disadvantage of a cut-through switch? Is there a way to solve this disadvantage of a cut-
through switch without losing the advantages?
Cut-through means the beginning of the data packet is leaving the switch before the end of the
packet has entered the switch. Disadvantage is errors are propagated. Not if you want to keep it
truly cut-through.
15. Give a common business example that mimics the differences between a shared network
segment and a dedicated network segment.
Wide range of possible answers here.
16. Your company’s switch between its two networks has just died. You have a router
lying on your desk that is not currently being used. Will the router work in place of the
broken bridge? Explain.
No. Routers operate on IP addresses, while switches operate on NIC addresses.
17. A CSMA/CD network is connected to the Internet via a router. A user on the
CSMA/CD network sends an e-mail to a user on the Internet. Show how the e-mail
message is encapsulated as it leaves the CSMA/CD network, enters the router, and then
leaves the router.
Leaving the LAN:
Data
App + Data
TCP + App + Data
IP + TCP + App + Data
MAC + IP + TCP + App + Data + MAC

Entering router:
MAC + IP + TCP + App + Data + MAC
Leaving router
WAN + IP + TCP + App + Data + WAN
18. Given the following network (Figure 7-22), show how the Spanning Tree Protocol will
eliminate the cyclic path.
The protocol will probably “remove” the bottom link on the far-right switch and the bottom link
on the switch immediately to the left of the far-right switch.
Thinking Outside the Box
1. You can interconnect all cash registers into one or two centrally located switches or hubs. Cat
5e/6 twisted pair should be sufficient. If hubs/switches can’t be centrally located and cable
distance exceeds 100 meters, be careful. Might need better medium. Can also connect using
multiplexing solution from earlier chapter.
Problems 2-6: Many possible solutions here.

Another Random Scribd Document
with Unrelated Content

ludicrous picture, than Mr. Fee Simple presents with his condemned
Saturday.
We have an esteem for ghost-inspectors, which it is utterly
impossible to extend to Day-fatalists. Mrs. Piptoss, too, may be
pitied; but Mog, turning her money when the moon makes her re-
appearance, is an object of ridicule. We shall neither be astonished,
nor express condolence, if the present, which Miss Caroline
anticipates from the knot in her lace, be not forthcoming; and as for
Miss Amelia, who has extinguished the candle, and to the best of her
belief lost her husband for a twelvemonth, we can only wish for her,
that when she is married, her lord and master will shake her faith in
the prophetic power of snuffers. But of all the superstitions that have
survived to the present time, and are to be found in force among
people of education and a thoughtful habit, Day-fatalism is the most
general, as it is the most unfounded and preposterous. It is a
superstition, however, in which many great and powerful thinkers
have shared, and by which they have been guided; it owes much of
its present influence to this fact; but reason, Christianity, and all we
have comprehended of the great scheme of which we form part,
alike tend to demonstrate its absurdity, and utter want of all
foundation.

"BATTLE WITH LIFE!"
Bear thee up bravely,
Strong heart and true!
Meet thy woes gravely,
Strive with them too!
Let them not win from thee
Tear of regret.
Such were a sin from thee,
Hope for good yet!
Rouse thee from drooping,
Care-laden soul;
Mournfully stooping
'Neath griefs control!
Far o'er the gloom that lies,
Shrouding the earth,
Light from eternal skies
Shows us thy worth.
Nerve thee yet stronger,
Resolute mind!
Let care no longer
Heavily bind.
Rise on thy eagle wings
Gloriously free!
Till from material things
Pure thou shalt be!
Bear ye up bravely,
Soul and mind too!
Droop not so gravely,
Bold heart and true!

Clear rays of streaming light
Shine through the gloom,
God's love is beaming bright
E'en round the tomb

TRIAL AND EXECUTION OF MADAME
ROLAND.
BY REV. JOHN S.C. ABBOTT.[17]
MADAME ROLAND.
The Girondists were led from their dungeons in the Conciergerie to
their execution on the 31st of October, 1793. Upon that very day
Madame Roland was conveyed from the prison of St. Pélagié to the
same gloomy cells vacated by the death of her friends. She was cast
into a bare and miserable dungeon, in that subterranean receptacle
of woe, where there was not even a bed. Another prisoner, moved

with compassion, drew his own pallet into her cell, that she might
not be compelled to throw herself for repose upon the cold, wet
stones. The chill air of winter had now come, and yet no covering
was allowed her. Through the long night she shivered with the cold.
The prison of the Conciergerie consists of a series of dark and damp
subterranean vaults, situated beneath the floor of the Palace of
Justice. Imagination can conceive of nothing more dismal than these
sombre caverns, with long and winding galleries opening into cells as
dark as the tomb. You descend by a flight of massive stone steps
into this sepulchral abode, and, passing through double doors,
whose iron strength time has deformed but not weakened, you enter
upon the vast labyrinthine prison, where the imagination wanders
affrighted through intricate mazes of halls, and arches, and vaults,
and dungeons, rendered only more appalling by the dim light which
struggles through those grated orifices which pierced the massive
walls. The Seine flows by upon one side, separated only by the high
way of the quays. The bed of the Seine is above the floor of the
prison. The surrounding earth was consequently saturated with
water, and the oozing moisture diffused over the walls and the floors
the humidity of the sepulchre. The plash of the river; the rumbling of
carts upon the pavements overhead; the heavy tramp of countless
footfalls, as the multitude poured into and out of the halls of justice,
mingled with the moaning of the prisoners in those solitary cells.
There were one or two narrow courts scattered in this vast structure,
where the prisoners could look up the precipitous walls, as of a well,
towering high above them, and see a few square yards of sky. The
gigantic quadrangular tower, reared above these firm foundations,
was formerly the imperial palace from which issued all power and
law. Here the French kings reveled in voluptuousness, with their
prisoners groaning beneath their feet. This strong-hold of feudalism
had now become the tomb of the monarchy. In one of the most
loathsome of these cells, Maria Antoinette, the daughter of the
Cæsars, had languished in misery as profound as mortals can suffer,
till, in the endurance of every conceivable insult, she was dragged to
the guillotine.

It was into a cell adjoining that which the hapless queen had
occupied that Madame Roland was cast. Here the proud daughter of
the emperors of Austria and the humble child of the artisan, each,
after a career of unexampled vicissitudes, found their paths to meet
but a few steps from the scaffold. The victim of the monarchy and
the victim of the Revolution were conducted to the same dungeons
and perished on the same block. They met as antagonists in the
stormy arena of the French Revolution. They were nearly of equal
age. The one possessed the prestige of wealth, and rank, and
ancestral power; the other, the energy of vigorous and cultivated
mind. Both were endowed with unusual attractions of person, spirits
invigorated by enthusiasm, and the loftiest heroism. From the
antagonism of life they met in death.
The day after Madame Roland was placed in the Conciergerie, she
was visited by one of the notorious officers of the revolutionary
party, and very closely questioned concerning the friendship she had
entertained for the Girondists. She frankly avowed the elevated
affection and esteem with which she cherished their memory, but
she declared that she and they were the cordial friends of republican
liberty; that they wished to preserve, not to destroy, the
Constitution. The examination was vexatious and intolerant in the
extreme. It lasted for three hours, and consisted in an incessant
torrent of criminations, to which she was hardly permitted to offer
one word in reply. This examination taught her the nature of the
accusations which would be brought against her. She sat down in
her cell that very night, and, with a rapid pen, sketched that defense
which has been pronounced one of the most eloquent and touching
monuments of the Revolution.
Having concluded it, she retired to rest, and slept with the serenity
of a child. She was called upon several times by committees sent
from the revolutionary tribunal for examination. They were resolved
to take her life, but were anxious to do it, if possible, under the
forms of law. She passed through all their examinations with the
most perfect composure, and the most dignified self-possession. Her

enemies could not withhold their expressions of admiration as they
saw her in her sepulchral cell of stone and of iron, cheerful,
fascinating, and perfectly at ease. She knew that she was to be led
from that cell to a violent death, and yet no faltering of soul could be
detected. Her spirit had apparently achieved a perfect victory over all
earthly ills.
The upper part of the door of her cell was an iron grating. The
surrounding cells were filled with the most illustrious ladies and
gentlemen of France. As the hour of death drew near, her courage
and animation seemed to increase. Her features glowed with
enthusiasm; her thoughts and expressions were refulgent with
sublimity, and her whole aspect assumed the impress of one
appointed to fill some great and lofty destiny. She remained but a
few days in the Conciergerie before she was led to the scaffold.
During those few days, by her example and her encouraging words,
she spread among the numerous prisoners there an enthusiasm and
a spirit of heroism which elevated, above the fear of the scaffold,
even the most timid and depressed. This glow of feeling and
exhilaration gave a new impress of sweetness and fascination to her
beauty. The length of her captivity, the calmness with which she
contemplated the certain approach of death, gave to her voice that
depth of tone and slight tremulousness of utterance which sent her
eloquent words home with thrilling power to every heart. Those who
were walking in the corridor, or who were the occupants of adjoining
cells, often called for her to speak to them words of encouragement
and consolation.
Standing upon a stool at the door of her own cell, she grasped with
her hands the iron grating which separated her from her audience.
This was her tribune. The melodious accents of her voice floated
along the labyrinthine avenues of those dismal dungeons,
penetrating cell after cell, and arousing energy in hearts which had
been abandoned to despair. It was, indeed, a strange scene which
was thus witnessed in these sepulchral caverns. The silence, as of
the grave, reigned there, while the clear and musical tones of

Madame Roland, as of an angel of consolation, vibrated through the
rusty bars, and along the dark, damp cloisters. One who was at that
time an inmate of the prison, and survived those dreadful scenes,
has described, in glowing terms, the almost miraculous effects of her
soul-moving eloquence. She was already past the prime of life, but
she was still fascinating. Combined with the most wonderful power
of expression, she possessed a voice so exquisitely musical, that,
long after her lips were silenced in death, its tones vibrated in
lingering strains in the souls of those by whom they had ever been
heard. The prisoners listened with the most profound attention to
her glowing words, and regarded her almost as a celestial spirit, who
had come to animate them to heroic deeds. She often spoke of the
Girondists who had already perished upon the guillotine. With
perfect fearlessness she avowed her friendship for them, and ever
spoke of them as our friends. She, however, was careful never to
utter a word which would bring tears into the eye. She wished to
avoid herself all the weakness of tender emotions, and to lure the
thoughts of her companions away from every contemplation which
could enervate their energies.
Occasionally, in the solitude of her cell, as the image of her husband
and of her child rose before her, and her imagination dwelt upon her
desolated home and her blighted hopes—her husband denounced
and pursued by lawless violence, and her child soon to be an orphan
—woman's tenderness would triumph over the heroine's stoicism.
Burying, for a moment, her face in her hands, she would burst into a
flood of tears. Immediately struggling to regain composure, she
would brush her tears away, and dress her countenance in its
accustomed smiles. She remained in the Conciergerie but one week,
and during that time so endeared herself to all as to become the
prominent object of attention and love. Her case is one of the most
extraordinary the history of the world has presented, in which the
very highest degree of heroism is combined with the most resistless
charms of feminine loveliness. An unfeminine woman can never be
loved by men. She may be respected for her talents, she may be
honored for her philanthropy, but she can not win the warmer

emotions of the heart. But Madame Roland, with an energy of will,
an inflexibility of purpose, a firmness of stoical endurance which no
mortal man has ever exceeded, combined that gentleness, and
tenderness, and affection—that instinctive sense of the proprieties of
her sex—which gathered around her a love as pure and as
enthusiastic as woman ever excited. And while her friends, many of
whom were the most illustrious men in France, had enthroned her as
an idol in their hearts, the breath of slander never ventured to
intimate that she was guilty even of an impropriety.
The day before her trial, her advocate, Chauveau de la Garde, visited
her to consult respecting her defense. She, well aware that no one
could speak a word in her favor but at the peril of his own life, and
also fully conscious that her doom was already sealed, drew a ring
from her finger, and said to him,
"To-morrow, I shall be no more. I know the fate which awaits me.
Your kind assistance can not avail aught for me, and would but
endanger you. I pray you, therefore, not to come to the tribunal, but
to accept of this last testimony of my regard."
The next day she was led to her trial. She attired herself in a white
robe, as a symbol of her innocence, and her long dark hair fell in
thick curls on her neck and shoulders. She emerged from her
dungeon the vision of unusual loveliness. The prisoners who were
walking in the corridors gathered around her, and with smiles and
words of encouragement she infused energy into their hearts. Calm
and invincible she met her judges. She was accused of the crimes of
being the wife of M. Roland and the friend of his friends. Proudly she
acknowledged herself guilty of both those charges. Whenever she
attempted to utter a word in her defense, she was brow-beaten by
the judges, and silenced by the clamors of the mob which filled the
tribunal. The mob now ruled with undisputed sway in both legislative
and executive halls. The serenity of her eye was untroubled, and the
composure of her disciplined spirit unmoved, save by the exaltation
of enthusiasm, as she noted the progress of the trial, which was
bearing her rapidly and resistlessly to the scaffold. It was, however,

difficult to bring any accusation against her by which, under the
form of law, she could be condemned. France, even in its darkest
hour, was rather ashamed to behead a woman, upon whom the eyes
of all Europe were fixed, simply for being the wife of her husband
and the friend of his friends. At last the president demanded of her
that she should reveal her husband's asylum. She proudly replied,
"I do not know of any law by which I can be obliged to violate the
strongest feelings of nature."
This was sufficient, and she was immediately condemned. Her
sentence was thus expressed:
"The public accuser has drawn up the present indictment against
Jane Mary Phlippon, the wife of Roland, late Minister of the Interior,
for having wickedly and designedly aided and assisted in the
conspiracy which existed against the unity and indivisibility of the
Republic, against the liberty and safety of the French people, by
assembling at her house, in secret council, the principal chiefs of
that conspiracy, and by keeping up a correspondence tending to
facilitate their treasonable designs. The tribunal having heard the
public accuser deliver his reasons concerning the application of the
law, condemns Jane Mary Phlippon, wife of Roland, to the
punishment of death."
She listened calmly to her sentence, and then rising, bowed with
dignity to her judges, and, smiling, said,
"I thank you, gentlemen, for thinking me worthy of sharing the fate
of the great men whom you have assassinated. I shall endeavor to
imitate their firmness on the scaffold."
With the buoyant step of a child, and with a rapidity which almost
betokened joy, she passed beneath the narrow portal, and
descended to her cell, from which she was to be led, with the
morning light, to a bloody death. The prisoners had assembled to
greet her on her return, and anxiously gathered around her. She
looked upon them with a smile of perfect tranquillity, and, drawing

her hand across her neck, made a sign expressive of her doom. But
a few hours elapsed between her sentence and her execution. She
retired to her cell, wrote a few words of parting to her friends,
played upon a harp, which had found its way into the prison, her
requiem, in tones so wild and mournful, that, floating in the dark
hours of the night, through these sepulchral caverns, they fell like
unearthly music upon the despairing souls there incarcerated.
The morning of the 10th of November, 1793, dawned gloomily upon
Paris. It was one of the darkest days of that reign of terror which,
for so long a period enveloped France in its sombre shades. The
ponderous gates of the court-yard of the Conciergerie opened that
morning to a long procession of carts loaded with victims for the
guillotine. Madame Roland had contemplated her fate too long, and
had disciplined her spirit too severely, to fail of fortitude in this last
hour of trial. She came from her cell scrupulously attired for the
bridal of death. A serene smile was upon her cheek, and the glow of
joyous animation lighted up her features as she waved an adieu to
the weeping prisoners who gathered around her. The last cart was
assigned to Madame Roland. She entered it with a step as light and
elastic as if it were a carriage for a pleasant morning's drive. By her
side stood an infirm old man, M. La Marche. He was pale and
trembling, and his fainting heart, in view of the approaching terror,
almost ceased to beat. She sustained him by her arm, and
addressed to him words of consolation and encouragement in
cheerful accents and with a benignant smile. The poor old man felt
that God had sent an angel to strengthen him in the dark hour of
death. As the cart heavily rumbled along the pavement, drawing
nearer and nearer to the guillotine, two or three times, by her
cheerful words, she even caused a smile faintly to play upon his
pallid lips.
The guillotine was now the principal instrument of amusement for
the populace of Paris. It was so elevated that all could have a good
view of the spectacle it presented. To witness the conduct of nobles
and of ladies, of boys and of girls, while passing through the horrors

of a sanguinary death, was far more exciting than the unreal and
bombastic tragedies of the theatre, or the conflicts of the cock-pit
and the bear garden. A countless throng flooded the streets; men,
women, and children, shouting, laughing, execrating. The celebrity
of Madame Roland, her extraordinary grace and beauty, and her
aspect, not only of heroic fearlessness, but of joyous exhilaration,
made her the prominent object of the public gaze. A white robe
gracefully enveloped her perfect form, and her black and glossy hair,
which for some reason the executioners had neglected to cut, fell in
rich profusion to her waist. A keen November blast swept the
streets, under the influence of which, and the excitement of the
scene, her animated countenance glowed with all the ruddy bloom
of youth. She stood firmly in the cart, looking with a serene eye
upon the crowds which lined the streets, and listening with unruffled
serenity to the clamor which filled the air. A large crowd surrounded
the cart in which Madame Roland stood, shouting, "To the guillotine!
to the guillotine!" She looked kindly upon them, and, bending over
the railing of the cart, said to them, in tones as placid as if she were
addressing her own child, "My friends, I am going to the guillotine.
In a few moments I shall be there. They who send me thither will
ere long follow me. I go innocent. They will come stained with
blood. You who now applaud our execution will then applaud theirs
with equal zeal."
Madame Roland had continued writing her memoirs until the hour in
which she left her cell for the scaffold. When the cart had almost
arrived at the foot of the guillotine, her spirit was so deeply moved
by the tragic scene—such emotions came rushing in upon her soul
from departing time and opening eternity, that she could not repress
the desire to pen down her glowing thoughts. She entreated an
officer to furnish her for a moment with pen and paper. The request
was refused. It is much to be regretted that we are thus deprived of
that unwritten chapter of her life. It can not be doubted that the
words she would then have written would have long vibrated upon
the ear of a listening world. Soul-utterances will force their way over

mountains, and valleys, and oceans. Despotism can not arrest them.
Time can not enfeeble them.
The long procession arrived at the guillotine, and the bloody work
commenced. The victims were dragged from the carts, and the ax
rose and fell with unceasing rapidity. Head after head fell into the
basket, and the pile of bleeding trunks rapidly increased in size. The
executioners approached the cart where Madame Roland stood by
the side of her fainting companion. With an animated countenance
and a cheerful smile, she was all engrossed in endeavoring to infuse
fortitude into his soul. The executioner grasped her by the arm.
"Stay," said she, slightly resisting his grasp; "I have one favor to ask,
and that is not for myself. I beseech you grant it me." Then turning
to the old man, she said, "Do you precede me to the scaffold. To see
my blood flow would make you suffer the bitterness of death twice
over. I must spare you the pain of witnessing my execution." The
stern officer gave a surly refusal, replying, "My orders are to take
you first." With that winning smile and that fascinating grace which
were almost resistless, she rejoined, "You can not, surely, refuse a
woman her last request." The hard-hearted executor of the law was
brought within the influence of her enchantment. He paused, looked
at her for a moment in slight bewilderment, and yielded. The poor
old man, more dead than alive, was conducted upon the scaffold
and placed beneath the fatal ax. Madame Roland, without the
slightest change of color, or the apparent tremor of a nerve, saw the
ponderous instrument, with its glittering edge, glide upon its deadly
mission, and the decapitated trunk of her friend was thrown aside to
give place for her. With a placid countenance and a buoyant step,
she ascended the platform. The guillotine was erected upon the
vacant spot between the gardens of the Tuileries and the Elysian
Fields, then known as the Place de la Revolution. This spot is now
called the Place de la Concorde. It is unsurpassed by any other place
in Europe. Two marble fountains now embellish the spot. The blood-
stained guillotine, from which crimson rivulets were ever flowing,
then occupied the space upon which one of these fountains has
been erected; and a clay statue to Liberty reared its hypocritical

front where the Egyptian obelisk now rises. Madame Roland stood
for a moment upon the elevated platform, looked calmly around
upon the vast concourse, and then bowing before the colossal
statue, exclaimed, "O Liberty! Liberty! how many crimes are
committed in thy name." She surrendered herself to the executioner,
and was bound to the plank. The plank fell to its horizontal position,
bringing her head under the fatal ax. The glittering steel glided
through the groove, and the head of Madame Roland was severed
from her body.
Thus died Madame Roland, in the thirty-ninth year of her age. Her
death oppressed all who had known her with the deepest grief. Her
intimate friend Buzot, who was then a fugitive, on hearing the
tidings, was thrown into a state of perfect delirium, from which he
did not recover for many days. Her faithful female servant was so
overwhelmed with grief, that she presented herself before the
tribunal, and implored them to let her die upon the same scaffold
where her beloved mistress had perished. The tribunal, amazed at
such transports of attachment, declared that she was mad, and
ordered her to be removed from their presence. A man-servant
made the same application, and was sent to the guillotine.
The grief of M. Roland, when apprized of the event, was unbounded.
For a time he entirely lost his senses. Life to him was no longer
endurable. He knew not of any consolations of religion. Philosophy
could only nerve him to stoicism. Privately he left, by night, the kind
friends who had hospitably concealed him for six months, and
wandered to such a distance from his asylum as to secure his
protectors from any danger on his account. Through the long hours
of the winter's night he continued his dreary walk, till the first gray
of the morning appeared in the east. Drawing a long stilletto from
the inside of his walking-stick, he placed the head of it against the
trunk of a tree, and threw himself upon the sharp weapon. The point
pierced his heart, and he fell lifeless upon the frozen ground. Some
peasants passing by discovered his body. A piece of paper was
pinned to the breast of his coat, upon which there were written

these words: "Whoever thou art that findest these remains, respect
them as those of a virtuous man. After hearing of my wife's death, I
would not stay another day in a world so stained with crime."
[From Dickens's Household Words.]

CHEMICAL CONTRADICTIONS.
Science, whose aim and end is to prove the harmony and "eternal
fitness of things," also proves that we live in a world of paradoxes;
and that existence itself is a whirl of contradictions. Light and
darkness, truth and falsehood, virtue and vice, the negative and
positive poles of galvanic or magnetic mysteries, are evidences of
all-pervading antitheses, which, acting like the good and evil genii of
Persian Mythology, neutralize each other's powers when they come
into collision. It is the office of science to solve these mysteries. The
appropriate symbol of the lecture-room is a Sphinx; for a scientific
lecturer is but a better sort of unraveler of riddles.
Who would suppose, for instance, that water—which every body
knows, extinguishes fire—may, under certain circumstances, add fuel
to flame, so that the "coming man," who is to "set the Thames on
fire," may not be far off. If we take some mystical gray-looking
globules of potassium (which is the metallic basis of common pearl-
ash) and lay them upon water, the water will instantly appear to
ignite. The globules will swim about in flames, reminding us of the
"death-fires" described by the Ancient Mariner, burning "like witches'
oil" on the surface of the stagnant sea. Sometimes even, without
any chemical ingredient being added, fire will appear to spring
spontaneously from water; which is not a simple element, as Thales
imagined, when he speculated upon the origin of the Creation, but
two invisible gases—oxygen and hydrogen, chemically combined.
During the electrical changes of the atmosphere in a thunder-storm,
these gases frequently combine with explosive violence, and it is this
combination which takes place when "the big rain comes dancing to
the earth." These fire-and-water phenomena are thus accounted for;
certain substances have peculiar affinities or attractions for one
another; the potassium has so inordinate a desire for oxygen, that
the moment it touches, it decomposes the water, abstracts all the

oxygen, and sets free the hydrogen or inflammable gas. The
potassium, when combined with the oxygen, forms that corrosive
substance known as caustic potash, and the heat, disengaged during
this process, ignites the hydrogen. Here the mystery ends; and the
contradictions are solved; Oxygen and hydrogen when combined,
become water; when separated the hydrogen gas burns with a pale,
lambent flame. Many of Nature's most delicate deceptions are
accounted for by a knowledge of these laws.
Your analytical chemist sadly annihilates, with his scientific
machinations, all poetry. He bottles up at pleasure the Nine Muses,
and proves them—as the fisherman in the Arabian Nights did the
Afrite—to be all smoke. Even the Will-o'-the-Wisp can not flit across
its own morass without being pursued, overtaken, and burnt out by
this scientific detective policeman. He claps an extinguisher upon
Jack-o'-Lantern thus: He says that a certain combination of
phosphorus and hydrogen, which rises from watery marshes,
produces a gas called phosphureted hydrogen, which ignites
spontaneously the moment it bubbles up to the surface of the water
and meets with atmospheric air. Here again the Ithuriel wand of
science dispels all delusion, pointing out to us, that in such places
animal and vegetable substances are undergoing constant
decomposition; and as phosphorus exists under a variety of forms in
these bodies, as phosphate of lime, phosphate of soda, phosphate of
magnesia, &c., and as furthermore the decomposition of water itself
is the initiatory process in these changes, so we find that
phosphorus and hydrogen are supplied from these sources; and we
may therefore easily conceive the consequent formation of
phosphureted hydrogen. This gas rises in a thin stream from its
watery bed, and the moment it comes in contact with the oxygen of
the atmosphere, it bursts into a flame so buoyant, that it flickers
with every breath of air, and realizes the description of Goethe's
Mephistopheles, that the course of Jack-o'-Lantern is generally "zig-
zag."

Who would suppose that absolute darkness may be derived from
two rays of light! Yet such is the fact. If two rays proceed from two
luminous points very close to each other, and are so directed as to
cross at a given point on a sheet of white paper in a dark room, their
united light will be twice as bright as either ray singly would
produce. But if the difference in the distance of the two points be
diminished only one-half, the one light will extinguish the other, and
produce absolute darkness. The same curious result may be
produced by viewing the flame of a candle through two very fine
slits near to each other in a card. So, likewise, strange as it may
appear, if two musical strings be so made to vibrate, in a certain
succession of degrees, as for the one to gain half a vibration on the
other, the two resulting sounds will antagonize each other and
produce an interval of perfect silence. How are these mysteries to be
explained? The Delphic Oracle of science must again be consulted,
and among the high priests who officiate at the shrine, no one
possesses more recondite knowledge, or can recall it more
instructively than Sir David Brewster. "The explanation which
philosophers have given," he observes, "of these remarkable
phenomena, is very satisfactory, and may easily be understood.
When a wave is made on the surface of a still pool of water by
plunging a stone into it, the wave advances along the surface, while
the water itself is never carried forward, but merely rises into a
height and falls into a hollow, each portion of the surface
experiencing an elevation and a depression in its turn. If we suppose
two waves equal and similar, to be produced by two separate stones,
and if they reach the same spot at the same time, that is, if the two
elevations should exactly coincide, they would unite their effects,
and produce a wave twice the size of either; but if the one wave
should be put so far before the other, that the hollow of the one
coincided with the elevation of the other, and the elevation of the
one with the hollow of the other, the two waves would obliterate or
destroy one another; the elevation, as it were, of the one filling up
half the hollow of the other, and the hollow of the one taking away
half the elevation of the other, so us to reduce the surface to a level.
These effects may be exhibited by throwing two equal stones into a

pool of water; and also may be observed in the Port of Batsha,
where the two waves arriving by channels of different lengths
actually obliterate each other. Now, as light is supposed to be
produced by waves or undulations of an ethereal medium filling all
nature, and occupying the pores of the transparent bodies; and as
sound is produced by undulations or waves in the air: so the
successive production of light and darkness by two bright lights, and
the production of sound and silence by two loud sounds, may be
explained in the very same manner as we have explained the
increase and obliteration of waves formed on the surface of water."
The apparent contradictions in chemistry are, indeed, best exhibited
in the lecture-room, where they may be rendered visible and
tangible, and brought home to the general comprehension. The
Professor of Analytical Chemistry, J.H. Pepper, who demonstrates
these things in the Royal Polytechnic Institution, is an expert
manipulator in such mysteries; and, taking a leaf out of his own
magic-book, we shall conjure him up before us, standing behind his
own laboratory, surrounded with all the implements of his art. At our
recent visit to this exhibition we witnessed him perform, with much
address, the following experiments: He placed before us a pair of tall
glass vessels, each filled, apparently, with water; he then took two
hen's eggs, one of these he dropped into one of the glass vessels,
and, as might have been expected, it immediately sank to the
bottom. He then took the other egg, and dropped it into the other
vessel of water, but, instead of sinking as the other had done, it
descended only half way, and there remained suspended in the
midst of the transparent fluid. This, indeed, looked like magic—one
of Houdin's sleight-of-hand performances—for what could interrupt
its progress? The water surrounding it appeared as pure below as
around and above the egg, yet there it still hung like Mahomet's
coffin, between heaven and earth, contrary to all the well-
established laws of gravity. The problem, however, was easily solved.
Our modern Cagliostro had dissolved in one half of the water in this
vessel as much common salt as it would take up, whereby the
density of the fluid was so much augmented that it opposed a

resistance to the descent of the egg after it had passed through the
unadulterated water, which he had carefully poured upon the briny
solution, the transparency of which, remaining unimpaired, did not
for a moment suggest the suspicion of any such impregnation. The
good housewife, upon the same principle, uses an egg to test the
strength of her brine for pickling.
Every one has heard of the power which bleaching gas (chlorine)
possesses in taking away color, so that a red rose held over its
fumes will become white. The lecturer, referring to this fact,
exhibited two pieces of paper; upon one was inscribed, in large
letters, the word "Proteus;" upon the other no writing was visible;
although he assured us the same word was there inscribed. He now
dipped both pieces of paper in a solution of bleaching-powder, when
the word "Proteus" disappeared from the paper upon which it was
before visible; while the same word instantly came out, sharp and
distinct, upon the paper which was previously a blank. Here there
appeared another contradiction: the chlorine in the one case
obliterating, and in the other reviving the written word; and how was
this mystery explained? Easily enough! Our ingenious philosopher, it
seems, had used indigo in penning the one word which had
disappeared; and had inscribed the other with a solution of a
chemical substance, iodide of potassium and starch; and the action
which took place was simply this: the chlorine of the bleaching
solution set free the iodine from the potassium, which immediately
combined with the starch, and gave color to the letters which were
before invisible. Again—a sheet of white paper was exhibited, which
displayed a broad and brilliant stripe of scarlet—(produced by a
compound called the bin-iodide of mercury)—when exposed to a
slight heat the color changed immediately to a bright yellow, and,
when this yellow stripe was crushed by smartly rubbing the paper,
the scarlet color was restored, with all its former brilliancy. This
change of color was effected entirely by the alteration which the
heat, in the one case, and the friction, in the other, produced in the
particles which reflected these different colors; and, upon the same
principle, we may understand the change of the color in the lobster-

shell, which turns from black to red in boiling; because the action of
the heat produces a new arrangement in the particles which
compose the shell.
With the assistance of water and fire, which have befriended the
magicians of every age, contradictions of a more marvelous
character may be exhibited, and even the secret art revealed of
handling red-hot metals, and passing through the fiery ordeal. If we
take a platinum ladle, and hold it over a furnace until it becomes of
a bright red heat, and then project cold water into its bowl, we shall
find that the water will remain quiescent and give no sign of
ebullition—not so much as a single "fizz;" but, the moment the ladle
begins to cool, it will boil up and quickly evaporate. So also, if a
mass of metal, heated to whiteness, be plunged in a vessel of cold
water, the surrounding fluid will remain tranquil so long as the
glowing white heat continues; but, the moment the temperature
falls, the water will boil briskly. Again—if water be poured upon an
iron sieve, the wires of which are made red hot, it will not run
through; but, on the sieve cooling, it will run through rapidly. These
contradictory effects are easily accounted for. The repelling power of
intense heat keeps the water from immediate contact with the
heated metal, and the particles of the water, collectively, retain their
globular form; but, when the vessel cools, the repulsive power
diminishes, and the water coming into closer contact with the heated
surface its particles can no longer retain their globular form, and
eventually expand into a state of vapor. This globular condition of
the particles of water will account for many very important
phenomena; perhaps it is best exhibited in the dew-drop, and so
long as these globules retain their form, water will retain its fluid
properties. An agglomeration of these globules will carry with them,
under certain circumstances, so much force that it is hardly a
contradiction to call water itself a solid. The water-hammer, as it is
termed, illustrates this apparent contradiction. If we introduce a
certain quantity of water into a long glass tube, when it is shaken,
we shall hear the ordinary splashing noise as in a bottle; but, if we
exhaust the air, and again shake the tube, we shall hear a loud

ringing sound, as if the bottom of the tube were struck by some
hard substance—like metal or wood—which may fearfully remind us
of the blows which a ship's side will receive from the waves during a
storm at sea, which will often carry away her bulwarks.
It is now time to turn to something stronger than water for more
instances of chemical contradictions. The chemical action of certain
poisons (the most powerful of all agents), upon the human frame,
has plunged the faculty into a maze of paradoxes; indeed, there is
actually a system of medicine, advancing in reputation, which is
founded on the principle of contraries. The famous Dr. Hahnemann,
who was born at Massieu in Saxony, was the founder of it, and,
strange to say, medical men, who are notorious for entertaining
contrary opinions, have not yet agreed among themselves whether
he was a very great quack or a very great philosopher. Be this as it
may, the founder of this system, which is called Homœopathy, when
translating an article upon bark in Dr. Cullen's Materia Medica, took
some of this medicine, which had for many years been justly
celebrated for the cure of ague. He had not long taken it, when he
found himself attacked with aguish symptoms, and a light now
dawned upon his mind, and led him to the inference that medicines
which give rise to the symptoms of a disease, are those which will
specifically cure it, and however curious it may appear, several
illustrations in confirmation of this principle were speedily found. If a
limb be frost-bitten, we are directed to rub it with snow; if the
constitution of a man be impaired by the abuse of spirituous liquors,
and he be reduced to that miserable state of enervation when the
limbs tremble and totter, and the mind itself sinks into a state of low
muttering delirium, the physician to cure him must go again to the
bottle and administer stimulants and opiates.
It was an old Hippocratic aphorism that two diseases can not co-
exist in the same body, wherefore, gout has actually been cured by
the afflicted person going into a fenny country and catching the
ague. The fatality of consumption is also said to be retarded by a
common catarrh; and upon this very principle depends the truth of

the old saying, that rickety doors hang long on rusty hinges. In other
words, the strength of the constitution being impaired by one
disease has less power to support the morbid action of another.
We thus live in a world of apparent contradictions; they abound in
every department of science, and beset us even in the sanctuary of
domestic life. The progress of discovery has reconciled and
explained the nature of some of them; but many baffle our
ingenuity, and still remain involved in mystery. This much, however,
is certain, that the most opposed and conflicting elements so
combine together as to produce results, which are strictly in unison
with the order and harmony of the universe.

DESCENT INTO THE CRATER OF A
VOLCANO.[18]
BY REV. H.T. CHEEVER.
A descent into the Crater of the Volcano of Kilauea in the Sandwich
Islands, may be accomplished with tolerable ease by the north-
eastern cliff of the crater, where the side has fallen in and slidden
downward, leaving a number of huge, outjutting rocks, like giants'
stepping-stones, or the courses of the pyramid of Ghizeh.
By hanging to these, and the mere aid of a pole, you may descend
the first precipice to where the avalanche brought up and was
stayed—a wild region, broken into abrupt hills and deep glens,
thickly set with shrubs and old ohias, and producing in great
abundance the Hawaiian whortleberry (formerly sacred to the
goddess of the volcano), and a beautiful lustrous blackberry that
grows on a branching vine close to the ground. Thousands of birds
find there a safe and warm retreat; and they will continue, I
suppose, the innocent warblers, to pair and sing there, till the fires
from beneath, having once more eaten through its foundations, the
entire tract, with all its miniature mountains and woody glens, shall
slide off suddenly into the abyss below to feed the hunger of all-
devouring fire.
No one who passes over it, and looks back upon the tall, jagged
cliffs at the rear and side, can doubt that it was severed and
shattered by one such ruin into its present forms. And the
bottomless pits and yawning caverns, in some places ejecting hot
steam, with which it is traversed, prove that the raging element
which once sapped its foundations is still busy beneath.

The path that winds over and down through this tract, crossing
some of these unsightly seams by a natural bridge of only a foot's
breadth, is safe enough by daylight, if one will keep in it. But be
careful that you do not diverge far on either side, or let the shades
of night overtake you there, lest a single mis-step in the grass and
ferns, concealing some horrible hole, or an accidental stumble, shall
plunge you beyond the reach of sunlight into a covered pen-stock of
mineral fire, or into the heart of some deep, sunken cavern.
One can hardly wander through that place alone, even in the
daytime (as I was in coming up from the crater at evening), without
having his fancy swarm with forms of evil. In spite of himself, there
will
"Throng thick into his mind the busy shapes
Of cover'd pits, unfathomably deep,
A dire descent! of precipices huge—
Rocks, caves, lakes, fens, bogs, dens, and shades of
death."
The way through this tract descends not abruptly for about half a
mile, to a steep bank of partially decomposed lava, somewhat
furrowed by water-courses, by which you go down some hundreds
of feet more to what every body calls the Black Ledge.
This is an immense rampart or gallery of grisly black scoria and lava,
about half a mile wide, running all round the pit, slightly sloping
inward, and not unfrequently overflowed in eruptions. By it you learn
the dimensions of the great lake to which this is now the shore. It
may be compared to the wide beach of an ocean, seldom flooded all
over except in very high tides; or to a great field of thick shore ice,
from under which the tide has retired, leaving it cracked and rent,
but not so as to break up the general evenness of its surface.
The upper crust is generally glossy, cellular, and cinder-like, brittle
and crackling under the feet; but directly underneath the superficies,
hard and compact, as proved by inspecting the great seams and

fissures, from some of which flickering currents of hot air, and from
others scalding steam and smoke are continually issuing. Pound on
it, and you will hear deep, hollow reverberations, and sometimes
your pole will break through a place like the rotten trap-door of
some old ruin, and open upon you a hideous black hole without
bottom.
Over this great volcanic mole or offset, we proceeded to make our
way toward the caldron in the southeast, pounding before us with
our pole, like men crossing a river to find whether the ice ahead will
bear them. We stopped every now and then to examine and get up
on to some great cone or oven, which had been formed after the
congelation of the crust, by pent up gas blowing out from beneath
the cooling lava, raising it as in great bubbles, and letting its black,
viscous vomit dribble from the top, and flow down sluggishly and
congeal before it had found a level, like ice in very cold weather over
a waterfall. Thus it would flow over the Black Ledge, hardening
sometimes in round streams like a cable, or in serpentine forms like
a great anaconda; and again it would spread out from the foot of
the cone a little way, in forms like a bronze lion's foot.
The surface was frequently broken, or ready to break, with the
weight of one's body, from the fiery liquid having subsided after the
petrifaction of the crust. Generally, too, the hardened lava seemed to
have been flowed over, like ice near the shore when the tide rises
and goes down, with a thin scum of lava that became shelly and
crepitated under the foot like shelly ice.
Then, as we went further into the bed of the crater, gradually going
down, we would come to places where, like as in frozen mill-ponds,
whence the water has been drawn off, the congealed lava had
broken in to the depth sometimes of fifty and one hundred feet.
Every where, too, there were great fissures and cracks, as in fields
of river ice, now and then a large air-hole, and here and there great
bulges and breaks, and places from which a thin flame would be
curling, or over which you would see a glimmer like that which

trembles over a body of fresh coals or a recently-burned lime-kiln.
Touch your stick there, and it would immediately kindle.
There were also deep, wide ditches, through which a stream of
liquid lava had flowed since the petrifaction of the main body
through which it passed. Cascades of fire are said to be often seen
in the course of these canals or rivers as they leap some precipice,
presenting in the night a scene of unequaled splendor and sublimity.
In some places the banks or dikes of these rivers are excavated and
fallen in with hideous crash and ruin; and often you may go up, if
you dare, to the edge on one side and look over into the gulf, and
away under the opposite overhanging bank, where the igneous fluid
has worn away and scooped it out till the cliff hangs on air, and
seems to topple and lean, like the tower of Pisa, just ready to fall.
It would be no very comfortable reflection, if a man were not too
curiously eager and bold and intent upon the novelties he is drinking
in by the senses, to have much reflection or fear at such a time, to
think how easily an earthquake might tumble down the bank on
which he is standing, undermined in like manner with that which you
are looking at right opposite.
On our left, as we passed on to the Great Caldron, we explored, as
far as was possible between the heat and vapor, the great bank, or,
more properly, mountain-side of sulphur and sulphate of lime
(plaster of Paris), and obtained some specimens of no little beauty.
There are cliffs of sulphur through which scalding hot vapor is
escaping as high up above you as eight hundred feet; and lower
down there are seams from which lambent and flickering flames are
darting, and jets of hot air will sometimes whirl by you, involving no
little danger by their inhalation. Around these fissures are yellow and
green incrustations of sulphur, which afford a new variety of
specimens.
When we had got to the leeward of the caldron, we found large
quantities of the finest threads of metallic vitrified lava, like the
spears and filaments of sealing-wax, called Pele's hair. The wind has

caught them from the jets and bubbling springs of gory lava, and
carried them away on its wings till they have lodged in nests and
crevices, where they may be collected like shed wool about the time
of sheep-shearing. Sometimes this is found twenty miles to the
leeward of the volcano.
The heat and sulphur gas, irritating the throat and lungs, are so
great on that side, that we had to sheer away off from the brim of
the caldron, and could not observe close at hand the part where
there was the most gushing and bubbling of the ignifluous mineral
fluid. But we passed round to the windward, and were thus enabled
to get up to the brim so as to look over for a minute in the molten
lake, burning incessantly with brimstone and fire—
"A furnace formidable, deep, and wide,
O'erboiling with a mad, sulphureous tide."
But the lava which forms your precarious foothold, melted, perhaps,
a hundred times, can not be handled or trusted, and the heat even
there is so great as to burn the skin of one's face, although the
heated air, as it rises, is instantly swept off to the leeward by the
wind. It is always hazardous, not to say fool-hardy, to stand there
for a moment, lest your uncertain foothold, crumbling and crispy by
the action of fire, shall suddenly give way and throw you instantly
into the fiery embrace of death.
At times, too, the caldron is so furiously boiling, and splashing, and
spitting its fires, and casting up its salient, angry jets of melted lava
and spume, that all approach to it is forbidden. We slumped several
times near it, as a man will in the spring who is walking over a river
of which the ice is beginning to thaw, and the upper stratum, made
of frozen snow, is dissolved and rotten. A wary native who
accompanied us wondered at our daring, and would not be kept
once from pulling me back, as with the eager and bold curiosity of a
discoverer, all absorbed in the view of such exciting wonders, I was
getting too near.

At the time we viewed it, the brim all round was covered with
splashes and spray to the width of ten or twelve feet. The surface of
the lake was about a mile in its longest diameter, at a depth of thirty
or forty feet from its brim, and agitated more or less all over, in
some places throwing up great jets and spouts of fiery red lava, in
other places spitting it out like steam from an escape-pipe when the
valves are half lifted, and again squirting the molten rock as from a
pop-gun.
The surface was like a river or lake when the ice is going out and
broken up into cakes, over which you will sometimes see the water
running, and sometimes it will be quite hidden. In the same manner
in this lake of fire, while its surface was generally covered with a
crust of half-congealed, dusky lava, and raised into elevations, or
sunk into depressions, you would now and then see the live coal-red
stream running along. Two cakes of lava, also, would meet like cakes
of ice, and their edges crushing, would pile up and fall over, precisely
like the phenomena of moving fields of ice; there was, too, the same
rustling, grinding noise.
Sometimes, I am told, the roar of the fiery surges is like the heavy
beating of surf. Once, when Mr. Coan visited it, this caldron was
heaped up in the middle, higher above its brim than his head, so
that he ran up and thrust in a pyrometer, while streams were
running off on different sides. At another time when he saw it, it had
sunk four or five hundred feet below its brim, and he had to look
down a dreadful gulf to see its fires.
Again, when Mr. Bingham was there, it was full, and concentric
waves were flowing out and around from its centre. Having carefully
observed its movements a while, he threw a stick of wood upon the
thin crust of a moving wave where he thought it would bear him,
even if it should bend a little, and then stood upon it a few
moments. In that position, thrusting his cane down through the
cooling tough crust, about half an inch thick, and immediately
withdrawing it, forthwith there gushed up, like ooze in a marsh or
melted tar under a plank, enough of the viscid lava to form a

globular mass, which afterward, as it cooled, he broke off and bore
away.
It is not easy for one that has not himself been in a similar position,
to sympathize with and pardon the traveler at such a point, for he is
unwilling to forbear and leave it till fairly surfeited and seared with
heat and admiration, or driven off by some sudden spout and roar,
or splash of the caldron. You gaze, and gaze, and gaze in
amazement, without conscious thought, like a man in a trance,
reluctant to go away, and you want to spend at least a day and
night, viewing close at hand its ever-varying phenomena.
Had we only brought with us wrappers, I believe we should have
been the first to have slept on the Black Ledge. Now that the edge
of curiosity is a little blunted and the judgment cool, we can see that
there would be a degree of hazard and temerity in it which is not felt
under the excitement of novelty, and in the full tide of discovery.
Forced by startling admonitions, of instant danger, I had to quit
suddenly the precarious footing I had gained on the caldron's edge,
like a hungry man hurried from his repast ere he has snatched a
mouthful. But the look I caught there, and the impression of horror,
awfulness, and sublimity thence obtained, live and will live in my
conscious being forever and ever; and it is this shall help me utter
what many have experienced, and have wished to say before the
poet said it for them:
"One compact hour of crowded life
Is worth an age without a name."
A moment of being under such circumstances is an epoch in the
history of one's mind; and he, perhaps, may be deemed the most
highly favored of mortals who has the most of such epochs in
remembrance, provided only that the incommunicable thoughts and
emotions which, in the moment of that experience, seemed to
permeate the very substance of the mind, have given it a moral tone
and impulse running through all its subsequent life. It is thus that
thoughts are waked "to perish never," being instamped ineffaceably

upon the spiritual frame-work and foundation stones of the soul,
dignifying and consecrating them to noble uses.
It was not, I trust, without some valuable additions to our stock of
impressions in this line, that we reluctantly left that spot. Departing
thence, we passed over a tract between the level of the brim of the
caldron and the Black Ledge, in order to gain again the latter, most
strangely rugged and wild, as if convulsion after convulsion had
upheaved, and sunk, and rent, and piled the vast mineral and rocky
masses; forming here great hills like the ruins of a hundred towers,
and there deep indentations, while every block lay upon its fellow,
ready to be dislodged, edge-wise, crosswise, endwise, sidewise,
angle-wise, and every-wise, in the wildest confusion and variety
possible, as if Typhœan giants had been hurling them at each other
in war; or as when the warring angels
"From their foundations loosening to and fro,
Uptore the seated hills, with all their load,
And sent them thundering upon their adversaries.
Then hills amid the air encounter'd hills,
Hurled to and fro with jaculation dire:
Horrid confusion heap'd upon confusion rose."
Rocks, too, in earthquake commotions, have been started from the
perpendicular sides of the crater in this part, and have rolled down
eight hundred or a thousand feet with a force, one might think, that
would almost shake the world.
When we had thus encompassed the crater, and had returned to the
point where we first came down upon the Black Ledge, it was
getting toward night, and I found myself so excessively heated and
feverish, and throbbing with the headache, which most persons
there suffer from, as to be unable to go for the castellated and
Gothic specimens into some ovens that are found in the sides near
by.

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