conclusion that at least one large marine animal exists which has not
as yet been classified among the known species of the present era. It
would appear that this animal has certainly a serpentine neck, and a
head small compared with its body, but large compared with the diameter
of the neck. It is probably an air-breather and warm-blooded, and
certainly carnivorous. Its propulsive power is great and apparently
independent of undulations of its body, wherefore it presumably
has powerful concealed paddles. All these circumstances correspond
with the belief that it is a modern representative of the long-neck
plesiosaurians of the great secondary or mesozoic era, a member of that
strange family of animals whose figure has been compared to that which
would be formed by drawing a serpent through the body of a sea-turtle.
Against this view sundry objections have been raised, which must now be
briefly considered.
In the first place, Professor Owen pointed out that the sea-saurians
of the secondary period have been replaced in the tertiary and present
seas by the whales and allied races. No whales are found in the
secondary strata, no saurians in the tertiary. “It seems to me less
probable,” he says, “that no part of the carcase of such reptiles
should have ever been discovered in a recent unfossilized state, than
that men should have been deceived by a cursory view of a partly
submerged and rapidly moving animal which might only be strange to
themselves. In other words, I regard the negative evidence from the
utter absence of any of the recent remains of great sea-serpents,
krakens, or enaliosauria, as stronger against their actual existence,
than the positive statements which have hitherto weighed with the
public mind in favour of their existence. A larger body of evidence
from eye-witnesses might be got together in proof of ghosts than of the
sea-serpent.”
To this it has been replied that genera are now known to exist, as the
_Chimæra_, the long-necked river tortoise, and the iguana, which are
closely related to forms which existed in the secondary era, while no
traces have been found of them in any of the intermediate or tertiary
strata. The chimæra is a case precisely analogous to the supposed case
of the enaliosaurus, for the chimæra is but rarely seen, like the
supposed enaliosaurus, is found in the same and absent from the same
fossiliferous strata. Agassiz is quoted in the _Zoologist_, page 2395,
as saying that it would be in precise conformity with analogy that such
an animal as the enaliosaurus should exist in the American seas, as
he had found numerous instances in which the fossil forms of the Old
World were represented by living types in the New. In close conformity
with this opinion is a statement made by Captain the Hon. George Hope,
that when in the British ship _Fly_, in the Gulf of California, the
sea being perfectly calm and transparent, he saw at the bottom a large
marine animal, with the head and general figure of an alligator, but
the neck much longer, and with four large paddles instead of legs.
Here, then, unless this officer was altogether deceived, which seems
quite unlikely under the circumstances, was a veritable enaliosaurus,
though of a far smaller species, probably, than the creature mistaken
for a sea-serpent.
As for the absence of remains, Mr. Darwin has pointed out that
the fossils we possess are but fragments accidentally preserved
by favouring circumstances in an almost total wreck. We have many
instances of existent creatures, even such as would have a far better
chance of floating after death, and so getting stranded where their
bones might be found, which have left no trace of their existence. A
whale possessing two dorsal fins was said to have been seen by Smaltz,
a Sicilian naturalist; but the statement was rejected, until a shoal
of these whales were seen by two eminent French zoologists, MM. Quoy
and Gaimard. No carcase, skeleton, or bone of this whale has ever
been discovered. For seventeen hours a ship, in which Mr. Gosse was
travelling to Jamaica, was surrounded by a species of whale never
before noticed—30 feet long, black above and white beneath, with
swimming paws white on the upper surface. Here, he says, was “a whale
of large size, occurring in great numbers in the North Atlantic, which
on no other occasion has fallen under scientific observation. The
toothless whale of Havre, a species actually inhabiting the British
Channel, is only known from a single specimen accidentally stranded on
the French coast; and another whale, also British, is known only from
a single specimen cast ashore on the Elgin roast, and there seen and
described by the naturalist Sowerby.
Dr. Andrew Wilson, in an interesting paper, in which he maintains that
sea-serpent tales are not to be treated with derision, but are worthy
of serious consideration, “supported as they are by zoological science,
and in the actual details of the case by evidence as trustworthy in
many cases as that received in our courts of law,” expresses the
opinion that plesiosauri and ichthyosauri have been unnecessarily
disinterred to do duty for the sea-serpents. But he offers as an
alternative only the ribbon-fish; and though some of these may attain
enormous dimensions, yet we have seen that some of the accounts of
the supposed sea-serpent, and especially the latest narrative by the
captain and crew of the _Pauline_, cannot possibly be explained by any
creature so flat and relatively so feeble as the ribbon-fish.
On the whole, it appears to me that a very strong case has been made
out for the enaliosaurian, or serpent-turtle, theory of the so-called
sea-serpent.
One of the ribbon-fish mentioned by Dr. Wilson, which was captured,
and measured more than 60 feet in length, might however fairly take
its place among strange sea creatures. I scarcely know whether to add
to the number a monstrous animal like a tadpole, or even more perhaps
like a gigantic skate, 200 feet in length, said to have been seen in
the Malacca Straits by Captain Webster and Surgeon Anderson, of the
ship _Nestor_. Perhaps, indeed, this monster, mistaken in the first
instance for a shoal, but presently found to be travelling along at
the rate of about ten knots an hour, better deserves to be called
a strange sea creature even than any of those which have been dealt
with in the preceding pages. But the only account I have yet seen
of Captain Webster’s statement, and Mr. Anderson’s corroboration,
appeared in an American newspaper; and though the story is exceedingly
well authenticated if the newspaper account of the matter is true, it
would not be at all a new feature in American journalism if not only
the story itself, but all the alleged circumstances of its narration,
should in the long run prove to be pure invention.
_ON SOME MARVELS IN TELEGRAPHY._
Within the last few years Electric Telegraphy has received some
developments which seem wonderful even by comparison with those other
wonders which had before been achieved by this method of communication.
In reality, all the marvels of electric telegraphy are involved, so
to speak, in the great marvel of electricity itself, a phenomenon
as yet utterly beyond the interpretation of physicists, though not
more so than its fellow marvels, light and heat. We may, indeed,
draw a comparison between some of the most wonderful results which
have recently been achieved by the study of heat and light and those
effected in the application of electricity to telegraphy. It is as
startling to those unfamiliar with the characteristics of light, or
rather with certain peculiarities resulting from these characteristics,
to be told that an astronomer can tell whether there is water in the
air of Mars or Venus, or iron vapour in the atmosphere of Aldebaran
or Betelgeux, as it is to those unfamiliar with the characteristics
of electricity, or with the results obtained in consequence of these
characteristics, to be told that a written message can be copied by
telegraph, a map or diagram reproduced, or, most wonderful of all,
a musical air correctly repeated, or a verbal message made verbally
audible. Telegraphic marvels such as these bear to the original marvel
of mere telegraphic communication, somewhat the same relation which
the marvels of spectroscopic analysis as applied to the celestial orbs
bear to that older marvel, the telescopic scrutiny of those bodies. In
each case, also, there lies at the back of all these marvels a greater
marvel yet—electricity in the one case, light in the other.
I propose in this essay to sketch the principles on which some of the
more recent wonders of telegraphic communication depend. I do not
intend to describe at any length the actual details or construction
of the various instruments employed. Precisely as the principles of
spectroscopic analysis can be made clear to the general reader without
the examination of the peculiarities of spectroscopic instruments,
so can the methods and principles of telegraphic communication be
understood without examining instrumental details. In fact, it may
be questioned whether general explanations are not in such cases
more useful than more detailed ones, seeing that these must of
necessity be insufficient for a student who requires to know the
subject practically in all its details, while they deter the general
reader by technicalities in which he cannot be expected to take any
interest. If it be asked, whether I myself, who undertake to explain
the principles of certain methods of telegraphic communication, have
examined _practically_ the actual instrumental working of these
methods, I answer frankly that I have not done so. As some sort
of proof, however, that without such practical familiarity with
working details the principles of the construction of instruments
may be thoroughly understood, I may remind the reader (see p. 96)
that the first spectroscopic battery I ever looked through—one in
which the dispersive power before obtained in such instruments had
been practically doubled—was of my own invention, constructed (with
a slight mechanical modification) by Mr. Browning, and applied at
once successfully to the study of the sun by Mr. Huggins, in whose
observatory I saw through this instrument the solar spectrum extended
to a length which, could it all have been seen at once, would have
equalled many feet.[27] On the other hand, it is possible to have a
considerable practical experience of scientific instruments without
sound knowledge of the principles of their construction; insomuch that
instances have been known in which men who have effected important
discoveries by the use of some scientific instrument, have afterwards
obtained their first clear conception of the principles of its
construction from a popular description.
It may be well to consider, though briefly, some of the methods of
communication which were employed before the electric telegraph was
invented. Some of the methods of electric telegraphy have their
antitypes, so to speak, in methods of telegraphy used ages before the
application of electricity. The earliest employment of telegraphy
was probably in signalling the approach of invading armies by beacon
fires. The use of this method must have been well known in the time
of Jeremiah, since he warns the Benjamites “to set up a sign of fire
in Beth-haccerem,” because “evil appeareth out of the north and great
destruction.” Later, instead of the simple beacon fire, combinations
were used. Thus, by an Act of the Scottish Parliament in 1455, the
blazing of one bale indicated the probable approach of the English, two
bales that they were coming indeed, and four bales blazing beside each
other that they were in great force. The smoke of beacon fires served
as signals by day, but not so effectively, except under very favourable
atmospheric conditions.
Torches held in the hand, waved, depressed, and so forth, were
anciently used in military signalling at night; while in the day-time
boards of various figures in different positions indicated either
different messages or different letters, as might be pre-arranged.
Hooke communicated to the Royal Society in 1684 a paper describing a
method of “communicating one’s mind at great distances.” The letters
were represented by various combinations of straight lines, which might
be agreed upon previously if secrecy were desired, otherwise the same
forms might represent constantly the same letters. With four straight
planks any letter of this alphabet could be formed as wanted, and being
then run out on a framework (resembling a gallows in Hooke’s picture),
could be seen from a distant station. Two curved beams, combined in
various ways, served for arbitrary signals.
Chappe, in 1793, devised an improvement on this in what was called
the T telegraph. An upright post supported a cross-bar (the top of
the T), at each end of which were the short dependent beams, making
the figure a complete Roman capital T. The horizontal bar as first
used could be worked by ropes within the telegraph-house, so as to be
inclined either to right or left. It thus had three positions. Each
dependent beam could be worked (also from within the house) so as to
turn upwards, horizontally, or downwards (regarding the top bar of
the T as horizontal), thus having also three positions. It is easily
seen that, since each position of one short beam could be combined
with each position of the other, the two together would present
three times three arrangements, or nine in all; and as these nine
could be given with the cross-bar in any one of its three positions,
there were in all twenty-seven possible positions. M. Chappe used an
alphabet of only sixteen letters, so that all messages could readily
be communicated by this telegraph. For shorter distances, indeed, and
in all later uses of Chappe’s telegraph, the short beams could be
used in intermediate positions, by which 256 different signals could
be formed. Such telegraphs were employed on a line beginning at the
Louvre and proceeding by Montmartre to Lisle, by which communications
were conveyed from the Committee of Public Welfare to the armies in the
Low Countries. Telescopes were used at each station. Barrère stated,
in an address to the Convention on August 17, 1794, that the news of
the recapture of Lisle had been sent by this line of communication to
Paris in one hour after the French troops had entered that city. Thus
the message was conveyed at the rate of more than 120 miles per hour.
Various other devices were suggested and employed during the first half
of the present century. The semaphores still used in railway signalling
illustrate the general form which most of these methods assumed. An
upright, with two arms, each capable of assuming six distinct positions
(excluding the upright position), would give forty-eight different
signals; thus each would give six signals alone, or twelve for the
pair, and each of the six signals of one combined with each of the six
signals of the other, would give thirty-six signals, making forty-eight
in all. This number suffices to express the letters of the alphabet
(twenty-five only are needed), the Arabic numerals, and thirteen
arbitrary signals.
The progress of improvement in such methods of signalling promised to
be rapid, before the invention of the electric telegraph, or rather,
before it was shown how the principle of the electric telegraph could
be put practically into operation. We have seen that they were capable
of transmitting messages with considerable rapidity, more than twice
as fast as we could now send a written message by express train. But
they were rough and imperfect. They were all, also, exposed to one
serious defect. In thick weather they became useless. Sometimes, at the
very time when it was most important that messages should be quickly
transmitted, fog interrupted the signalling. Sir J. Barrow relates that
during the Peninsular War grave anxiety was occasioned for several
hours by the interruption of a message from Plymouth, really intended
to convey news of a victory. The words transmitted were, “Wellington
defeated;” the message of which these words formed the beginning was:
“Wellington defeated the French at,” etc. As Barrow remarks, if the
message had run, “French defeated at,” etc., the interruption of the
message would have been of less consequence.
Although the employment of electricity as a means of communicating
at a distance was suggested before the end of the last century, in
fact, so far back as 1774, the idea has only been worked out during
the last forty-two years. It is curious indeed to note that until
the middle of the present century the word “telegraph,” which is now
always understood as equivalent to electric telegraph, unless the
contrary is expressed, was commonly understood to refer to semaphore
signalling,[28] unless the word “electric” were added.
The general principle underlying all systems of telegraphic
communication by electricity is very commonly misunderstood. The idea
seems to prevail that electricity can be sent out along a wire to any
place where some suitable arrangement has been made to receive it. In
one sense this is correct. But the fact that the electricity has to
make a circuit, returning to the place from which it is transmitted,
seems not generally understood. Yet, unless this is understood, the
principle, even the possibility, of electric communication is not
recognized.
Let us, at the outset, clearly understand the nature of electric
communication.
In a variety of ways, a certain property called electricity can be
excited in all bodies, but more readily in some than in others. This
property presents itself in two forms, which are called positive
and negative electricity, words which we may conveniently use, but
which must not be regarded as representing any real knowledge of
the distinction between these two kinds of electricity. In fact,
let it be remembered throughout, that we do not in the least know
what electricity is; we only know certain of the phenomena which
it produces. Any body which has become charged with electricity,
either positive or negative, will part with its charge to bodies in a
neutral condition, or charged with the opposite electricity (negative
or positive). But the transference is made much more readily to
some substances than to others—so slowly, indeed, to some, that in
ordinary experiments the transference may be regarded as not taking
place at all. Substances of the former kind are called good conductors
of electricity; those which receive the transfer of electricity less
readily are said to be bad conductors; and those which scarcely receive
it at all are called insulating substances. The reader must not
confound the quality I am here speaking of with readiness to become
charged with electricity. On the contrary, the bodies which most
freely receive and transmit electricity are least readily charged with
electricity, while insulating substances are readily electrified. Glass
is an insulator, but if glass is briskly rubbed with silk it becomes
charged (or rather, the part rubbed becomes charged) with positive
electricity, formerly called _vitreous_ electricity for this reason;
and again, if wax or resin, which are both good insulators, be rubbed
with cloth or flannel, the part rubbed becomes charged with negative,
formerly called _resinous_, electricity.
Electricity, then, positive or negative, however generated, passes
freely along conducting substances, but is stopped by an insulating
body, just as light passes through transparent substances, but is
stopped by an opaque body. Moreover, electricity may be made to pass
to any distance along conducting bodies suitably insulated. Thus, it
might seem that we have here the problem of distant communication
solved. In fact, the first suggestion of the use of electricity in
telegraphy was based on this property. When a charge of electricity has
been obtained by the use of an ordinary electrical machine, this charge
can be drawn off at a distant point, if a conducting channel properly
insulated connects that point with the bodies (of whatever nature)
which have been charged with electricity. In 1747, Dr. Watson exhibited
electrical effects from the discharges of Leyden jars (vessels
suitably constructed to receive and retain electricity) at a distance
of two miles from the electrical machine. In 1774, Le Sage proposed
that by means of wires the electricity developed by an electrical
machine should be transmitted by insulated wires to a point where an
electroscope, or instrument for indicating the presence of electricity,
should, by its movements, mark the letters of the alphabet, one wire
being provided for each letter. In 1798 Béthencourt repeated Watson’s
experiment, increasing the distance to twenty-seven miles, the
extremities of his line of communication being at Madrid and Aranjuez.
(Guillemin, by the way, in his “Applications of the Physical Forces,”
passes over Watson’s experiment; in fact, throughout his chapters on
the electric telegraph, the steam-engine, and other subjects, he seems
desirous of conveying as far as possible the impression that all the
great advances of modern science had their origin in Paris and its
neighbourhood.)
From Watson’s time until 1823 attempts were made in this country
and on the Continent to make the electrical machine serve as the
means of telegraphic communication. All the familiar phenomena of
the lecture-room have been suggested as signals. The motion of pith
balls, the electric spark, the perforation of paper by the spark, the
discharge of sparks on a fulminating pane (a glass sheet on which
pieces of tinfoil are suitably arranged, so that sparks passing from
one to another form various figures or devices), and other phenomena,
were proposed and employed experimentally. But practically these
methods were not effectual. The familiar phenomenon of the electric
spark explains the cause of failure. The spark indicates the passage of
electricity across an insulating medium—dry air—when a good conductor
approaches within a certain distance of the charged body. The greater
the charge of electricity, the greater is the distance over which the
electricity will thus make its escape. Insulation, then, for many miles
of wire, and still more for a complete system of communication such
as we now have, was hopeless, so long as frictional electricity was
employed, or considerable electrical intensity required.
We have now to consider how galvanic electricity, discovered in 1790,
was rendered available for telegraphic communication. In the first
place, let us consider what galvanic or voltaic electricity is.
I have said that electricity can be generated in many ways. It may
be said, indeed, that every change in the condition of a substance,
whether from mechanical causes, as, for instance, a blow, a series of
small blows, friction, and so forth, or from change of temperature,
moisture, and the like, or from the action of light, or from chemical
processes, results in the development of more or less electricity.
When a plate of metal is placed in a vessel containing some acid
(diluted) which acts chemically on the metal, this action generates
negative electricity, which passes away as it is generated. But if a
plate of a different metal, either not chemically affected by the acid
or less affected than the former, be placed in the dilute acid, the two
plates being only partially immersed and not in contact, then, when a
wire is carried from one plate to the other, the excess of positive
electricity in the plate least affected by the acid is conveyed to
the other, or, in effect, discharged; the chemical action, however,
continues, or rather is markedly increased, fresh electricity is
generated, and the excess of positive electricity in the plate least
affected is constantly discharged. Thus, along the wire connecting
the two metals a current of electricity passes from the metal least
affected to the metal most affected; a current of negative electricity
passes in a contrary direction in the dilute acid.