possession a copy of the device borne by the seal of Columbia College,
New York, executed for him by M. Dumoulin-Froment, within a circle less
than three one-hundredths of an inch in diameter, "in which are embraced
four human figures and various other objects, together with inscriptions
in Latin, Greek, and Hebrew, all clearly legible. In this device the
rising sun is represented in the horizon, the diameter of the disk being
about three one-thousandths of an inch. This disk has been cross-hatched
by the draughtsman in the original design from which the copy was made;
and the copy shows the marks of the cross-hatching with perfect
distinctness. When this beautiful and delicate drawing is brought
clearly out by a suitably adjusted illumination, the lines appear as if
traced by a smooth point in a surface of opaque ice."
Lardner, in his book on the "Microscope," published in 1856, gives a
wood cut which shows the first piece of engraving magnified 120
diameters, but he said that he was not at liberty to describe the method
by which it was done. As happens in almost all such cases, however, the
very secrecy with which the process was surrounded naturally stimulated
others to rival or surpass it, and Mr. N. Peters, a London banker,
turned his attention to the subject and soon invented a machine which
produced results far exceeding anything that M. Froment had
accomplished. On April 25, 1855, Mr. Farrants read before the
Microscopical Society of London a full account of the Peters machine,
with which the inventor had written the Lord's Prayer (in the ordinary
writing character, without abbreviation or contraction of any kind), in
a space not exceeding the one hundred and fifty-thousandth of a square
inch. Seven years later, Mr. Farrants, as President of the Microscopical
Society, described further improvements in the machine of Mr. Peters,
and made the following statement: "The Lord's Prayer has been written
and may be read in the one-three hundred and fifty-six thousandth of an
English square inch. The measurements of one of these specimens was
verified by Dr. Bowerbank, with a difference of not more than one
five-millionth of an inch, and that difference, small as it is, arose
from his not including the prolongation of the letter _f_ in the
sentence 'deliver us from evil'; so he made the area occupied by the
writing less than that stated above."
Some idea of the minuteness of the characters in these specimens may be
obtained from the statement that the whole Bible and Testament, in
writing of the same size, might be placed twenty-two times on the
surface of a square inch. The grounds for this startling assertion are
as follows: "The Bible and Testament together, in the English language,
are said to contain 3,566,480 letters. The number of letters in the
Lord's Prayer, as written, ending in the sentence, 'deliver us from
evil,' is 223, whence, as 3,566,480 divided by 223, is equal to 15,922,
it appears that the Bible and Testament together contain the same number
of letters as the Lord's Prayer written 16,000 times; if then the prayer
were written in 1-16,000 of an inch, the Bible and Testament in writing
of the same size would be contained by one square inch; but as
1-356,000th of an inch is one twenty-secondth part of 1-15,922 of an
inch, it follows that the Bible and Testament, in writing of that size,
would occupy less space than one twenty-secondth of a square inch."
It only now remains to be seen that, minute as are the letters written
by this machine, they are characterized by a clearness and precision of
form which proves that the moving parts of the machine, while possessing
the utmost delicacy of freedom, are absolutely destitute of shake, a
union of requisites very difficult of fulfilment, but quite
indispensable to the satisfactory performance of the apparatus.
I have no information in regard to the present whereabouts of any of the
specimens turned out by Mr. Peters, and inquiry in London, among persons
likely to know, has not supplied any information on the subject.
There was, however, another micrographer, Mr. William Webb, of London,
who succeeded in producing some marvellous results. Epigrams and also
the Lord's Prayer written in the one-thousandth part of a square inch
have been freely distributed. Mr. Webb also produced a few copies of the
second chapter of the Gospel, according to St. John, written on the
scale of the whole Bible, to a little more than three-quarters of a
square inch, and of the Lord's Prayer written on the scale of the whole
Bible eight times on a square inch. Mr. Webb died about fifteen years
ago, and I believe he has had no successor in the art. Specimens of his
work are quite scarce, most of them having found their way into the
cabinets of public Museums and Societies, who are unwilling to part with
them. The late Dr. Woodward, Director of the Army Medical Museum,
Washington, D.C., procured two of them on special order for the Museum.
Mr. Webb had brought out these fine writings as tests for certain
qualities of the microscope, and it was to "serve as tests for
high-power objectives" that Dr. Woodward procured the specimens now in
the microscopical department of the Museum. I am so fortunate as to have
in my possession two specimen's of Mr. Webb's work. One is an ordinary
microscopical glass slide, three inches by one, and in the center is a
square speck which measures 1-45th of an inch on the side. Upon this
square is written the whole of the second chapter of the Gospel
according to St. John--the chapter which contains the account of the
marriage in Cana of Galilee.
In order to estimate the space which the whole Bible would occupy if
written on the same scale as this chapter, I have made the following
calculation which, I think, will be more easily followed and checked by
my readers, than that of Mr. Farrants.
The text of the old version of the Bible, as published in minion by the
American Bible Society, contains 1272 pages, exclusive of title pages
and blanks. Each page contains two columns of 58 lines each, making 116
lines to the page. This includes the headings of the chapters and the
synopses of their contents, which are, therefore, thrown in to make good
measure. We have, therefore, 1272 pages of 116 lines each, making a
total of 147,552 lines.
The second chapter of St. John has 25 verses containing 95 lines, and is
written on the 1-2025th of an inch, or, in other words, it would go 2025
times on a square inch. A square inch would, therefore, contain 95 x
2025 or 192,375 lines. This number (192,375), divided by the number of
lines in the Bible (147,552), gives 1.307, which is the number of times
the Bible might be written on a square inch in letters of the same size.
In other words, the whole Bible might be written on .77 inch, or very
little more than three-quarters of a square inch.
Perhaps the following gives a more impressive illustration: The United
States silver quarter of a dollar is .95 inch in diameter, so that the
surface of each side is .707 of a square inch. The whole Bible would,
therefore, very nearly go on one side of a quarter of a dollar. If the
blank spaces at the heads of the chapters and the synopses of contents
were left out, it would easily go on one side.
The second specimen, which I have of Mr. Webb's writing, is a copy of
the Lord's Prayer written on a scale of eight Bibles to the square inch.
According to a statement kindly sent me by the superintendent of the
United States Mint at Philadelphia, the diameter of the last issued gold
dollar, and also of the silver half-dime, is six-tenths of an inch. This
gives .2827+ of a square inch as the area of the surface of one side,
and, therefore, the whole Bible might be written more than two and a
quarter times on one side of either the gold dollar or the silver half
dime.
Such numerical and space relations are far beyond the power of any
ordinary mind to grasp. With the aid of a microscope we can see the
object and compare with other magnifications the rate at which it is
enlarged, and a person of even the most ordinary education can follow
the calculation and understand why the statements are true, but the
final result, like the duration of eternity or the immensity of space,
conveys no definite idea to our minds.
But at the same time we must carefully distinguish between our want of
power to grasp these ideas and our inability to form a conception of
some inconceivable subject, such as a fourth dimension or the mode of
action of a new sense.
Wonderful as these achievements are, there is another branch of the
microscopic art which, from the practical applications that have been
made of it, is even more interesting. This is the art of
microphotography.
About the middle of the last century Mr. J. B. Dancer, of Manchester,
England, produced certain minute photographs of well-known pictures and
statues which commanded the universal attention of the microscopists of
that day, and for a time formed the center of attraction at all
microscopical exhibitions. They have now, however, become so common that
they receive no special notice. Mr. Dancer and other artists also
produced copies of the Lord's Prayer, the Creed, the Declaration of
Independence, etc., on such a scale that the Lord's Prayer might be
covered with the head of a common pin, and yet, when viewed under a very
moderate magnifying power, every letter was clear and distinct. I have
now before me a slip of glass, three inches long and one inch wide, in
the center of which is an oval photograph which occupies less than the
1-200th of a square inch. This photograph contains the Declaration of
Independence with the signatures of all the signers, surrounded by
portraits of the Presidents and the seals of the original thirteen
States. Under a moderate power every line is clear and distinct. In the
same way copies of such famous pictures as Landseer's "Stag at Bay,"
although almost invisible to the naked eye, come out beautifully clear
and distinct under the microscope, so that it has been suggested that
one might have an extensive picture gallery in a small box, or pack away
copies of all the books in the Congressional Library in a small
hand-bag. With such means at our command, it would be a simple matter to
condense a bulky dispatch into a few little films, which might be
carried in a quill or concealed in ways which would have been impossible
with the original. If Major Andre had been able to avail himself of this
mode of reducing the bulk of the original papers, he might have carried,
without danger of discovery, those reports which caused his capture and
led to his death. And hereafter the ordinary methods of searching
suspected spies will have to be exchanged for one that is more
efficient.
The most interesting application of microphotography, of which we have
any record, occurred during the Franco-Prussian war in 1870-71.
[Illustration: Fig. 21.]
On September 21, 1870, the Germans so completely surrounded the French
capitol, that all communication by roads, railways, and telegraphs, was
cut off and the only way of escape from the city was through the air. On
April 23, the first balloon left Paris, and in a short time after that,
a regular balloon post was established, letters and packages being sent
out at intervals of three to seven days. In order to get news back to
the city, carrier pigeons were employed, and at first the letters were
simply written on very thin paper and enclosed in quills which were
fastened to the middle tail-feather of the bird, as shown in the
engraving, Fig. 21. It is, of course, needless to say, that the
ordinary pictures of doves with letters tied round their necks or
love-notes attached to their wings, are all mere romance. A bird loaded
in that way would soon fall a prey to its enemies. As it was, some of
the pigeons were shot by German gunners or captured by hawks trained by
the Germans for the purpose, but the great majority got safely through.
Written communications, however, were of necessity, bulky and heavy, and
therefore M. Dagron, a Parisian photographer, suggested that the news be
printed in large sheets of which microphotographs could be made and
transferred to collodion positives which might then be stripped from the
glass and would be very light. This was done; the collodion pellicles
measuring about ten centimeters (four inches) square and containing
about three thousand average messages. Eighteen of these pellicles
weighed less than one gramme (fifteen grains) and were easily carried by
a single pigeon. The pigeons having been bred in Paris and sent out by
balloons, always returned to their dove-cotes in that city.
M. Dagron left Paris by balloon on November 12, and after a most
adventurous voyage, being nearly captured by a German patrol, he reached
Tours and there established his headquarters, and organized a regular
system of communication with the capitol. The results were most
satisfactory, upwards of two and a half millions of messages having been
sent into the city. Even postal orders, and drafts were transmitted in
this way and duly honored.
And thus through the pigeon-post, aided by microphotography, Paris was
enabled to keep in touch with the outer world, and the anxiety of
thousands of families was relieved.
It is not likely, however, that the pigeon-post will ever again come
into use for this purpose; our interest in it is now merely historical,
for in the next great siege, if we ever have one, the wireless telegraph
will no doubt take its place and messages, which no hawks can capture
and no guns can destroy, will be sent directly over the heads of the
besiegers.
But let us hope and pray, that the savage and unnecessary war which is
now being waged in the east will be the last, and that in the near
future, two or more of the great nations of the globe will so police the
world, that peace on earth and good will toward men will everywhere
prevail.
ILLUSIONS OF THE SENSES
Our senses have been called the "Five Gateways of Knowledge" because all
that we know of the world in which we live reaches the mind, either
directly or indirectly, through these avenues. From the "ivory palace,"
in which she dwells apart, and which we call the skull, the mind sends
forth her scouts--sight, hearing, feeling, taste, and smell--bidding
them bring in reports of all that is going on around her, and if the
information which they furnish should be untrue or distorted, the most
dire results might follow. She, therefore, frequently compares the tale
that is told by one with the reports from the others, and in this way it
is found that under some conditions these reporters are anything but
reliable; the stories which they tell are often distorted and untrue,
and in some cases their tales have no foundation whatever in fact, but
are the "unsubstantial fabric of a vision."
It is, therefore, of the greatest importance to us, that we should find
out the points on which these information bearers are most likely to be
deceived so that we may guard against the errors into which they would
otherwise certainly lead us.
All the senses are liable to be imposed upon under certain conditions.
The senses of taste and of smell are frequently the subject of phantom
smells and tastes, which are as vivid as the sensations produced by
physical causes acting in the regular way. Even those comparatively new
senses[9] which have been differentiated from the sense of touch and
which, with the original five, make up the mystic number seven, are very
untrustworthy guides under certain circumstances. Thus we all know how
the sense of heat may be deceived by the old experiment of placing one
hand in a bowl of cold water and the other in a bowl of hot water, and
then, after a few minutes, placing both hands together in a bowl of
tepid water; the hand, which has been in the cold water will feel warm,
while that which has just been taken from the hot water, will feel quite
cold.
We have all experienced the deceptions to which the sense of hearing
exposes us. Who has not heard sounds which had no existence except in
our own sensations? And every one is familiar with the illusions to
which we are liable when under the influence of a skilful ventriloquist.
Even the sense of touch, which most of us regard as infallible, is
liable to gross deception. When we have "felt" anything we are always
confident as to its shape, number, hardness, etc., but the following
very simple experiment shows that this confidence may be misplaced:
[Illustration: Fig. 22.]
Take a large pea or a small marble or bullet and place it on the table
or in the palm of the left hand. Then cross the fingers of the right
hand as shown in the engraving, Fig. 22, the second finger crossing the
first, and place them on the ball, so that the latter may lie between
the fingers, as figured in the cut. If the pea or ball be now rolled
about, the sensation is apparently that given by two peas under the
fingers, and this illusion is so strong that it cannot be dispelled by
calling in any of the other senses (the sense of sight for example) as
is usually the case under similar circumstances. We may try and try, but
it will only be after considerable experience that we shall learn to
disregard the apparent impression that there are two balls.
The cause of this illusion is readily found. In the ordinary position of
the fingers the same ball cannot touch at the same time the exterior
sides of two adjoining fingers. When the two fingers are crossed, the
conditions are exceptionally changed, but the instinctive interpretation
remains the same, unless a frequent repetition of the experiment has
overcome the effect of our first education on this point. The
experiment, in fact has to be repeated a great number of times to make
the illusion become less and less appreciable.
But of all the senses, that of sight is the most liable to error and
illusion, as the following simple illustrations will show.
[Illustration: Fig. 23.]
[Illustration: Fig. 24.]
In Fig. 23 a black spot has been placed on a white ground, and in Fig.
24 a white spot is placed on a black ground; which is the larger, the
black spot or the white one? To every eye the white spot will appear to
be the largest, but as a matter of fact they are both the same size.
This curious effect is attributed by Helmholtz to what is called
irradiation. The eye may also be greatly deceived even in regard to the
length of lines placed side by side. Thus, in Fig. 25 a thin vertical
line stands upon a thick horizontal one; although the two lines are of
precisely the same length, the vertical one seems to be considerably
longer than the other.
[Illustration: Fig. 25.]
In Figs. 26 and 27 a series of vertical and horizontal lines are shown,
and in both forms the space that is covered seems to be longer one way
than the other. As a matter of fact the space in each case is a perfect
square, and the apparent difference in width and height depends upon
whether the lines are vertical or horizontal.
[Illustration: Fig. 26.]
[Illustration: Fig. 27.]
Advantage is taken of this curious illusion in decorating rooms and in
selecting dresses. Stout ladies of taste avoid dress goods having
horizontal stripes, and ladies of the opposite conformation avoid those
in which the stripes are vertical.
But the greatest discrepancy is seen in Figs. 28 and 29, the middle line
in Fig. 29 appearing to be much longer than in Fig. 28. Careful
measurement will show that they are both of precisely the same length,
the apparent difference being due to the arrangement of the divergent
lines at the ends.
[Illustration: Fig. 28.]
[Illustration: Fig. 29.]
[Illustration: Fig. 30.]
Converging lines have a curious effect upon apparent size. Thus in Fig.
30 we have a wall and three posts, and if asked which of the posts was
the highest, most persons would name C, but measurement will show that A
is the highest and that C is the shortest.
[Illustration: Fig. 31.]
A still more striking effect is produced in two parallel lines by
crossing them with a series of oblique lines as seen in Figs. 31 and 32.
In Fig. 31 the horizontal lines seem to be much closer at the right-hand
ends than at the left, but accurate measurement will show that they are
strictly parallel.
By changing the direction of the oblique lines, as shown in Fig. 32, the
horizontal lines appear to be crooked although they are perfectly
straight.
[Illustration: Fig. 32.]
All these curious illusions are, however, far surpassed by an experiment
which we will now proceed to describe.
FOOTNOTES:
[9] The old and generally recognized list of the senses is as follows:
Sight, Hearing, Smell, Taste, and Touch. This is the list enumerated by
John Bunyan in his famous work, "The Holie Warre." It has, however, been
pointed out that the sense which enables us to recognize heat is not
quite the same as that of touch and modern physiologists have therefore
set apart, as a distinct sense, the power by which we recognize heat.
The same had been previously done in the case of the sense of Muscular
Resistance but, as the author of "The Natural History of Hell" says,
"when we differentiate the 'Sense of Heat,' and the 'Sense of
Resistance' from the Sense of Touch, we may set up new signposts, but we
do not open up any new 'gateways', things still remain as they were of
old, and every messenger from the material world around us must enter
the ivory palace of the skull through one of the old and well-known
ways."
OBJECTS APPARENTLY SEEN THROUGH A HOLE IN THE HAND
The following curious experiment always excites surprise, and as I have
met with very few persons who have ever heard of it, I republish it from
"The Young Scientist," for November, 1880. It throws a good deal of
light upon the facts connected with vision.
[Illustration: Fig. 33.]
Procure a paste-board tube about seven or eight inches long and an inch
or so in diameter, or roll up a strip of any kind of stiff paper so as
to form a tube. Holding this tube in the left hand, look through it
with the left eye, the right eye also being kept open. Then bring the
right hand into the position shown in the engraving, Fig. 33, the edge
opposite the thumb being about in line with the right-hand side of the
tube. Or the right hand may rest against the right-hand side of the
tube, near the end farthest from the eye. This cuts off entirely the
view of the object by the right eye, yet strange to say the object will
still remain apparently visible to both eyes through a hole in the hand,
as shown by the dotted lines in the engraving! In other words, it will
appear to us as if there was actually a hole through the hand, the
object being seen through that hole. The result is startlingly
realistic, and forms one of the simplest and most interesting
experiments known.
This singular optical illusion is evidently due to the sympathy which
exists between the two eyes, from our habit of blending the images
formed in both eyes so as to give a single image.
LOOKING THROUGH A SOLID BRICK
A very common exhibition by street showmen, and one which never fails to
excite surprise and draw a crowd, is the apparatus by which a person is
apparently enabled to look through a brick. Mounted on a simple-looking
stand are a couple of tubes which look like a telescope cut in two in
the middle. Looking through what most people take for a telescope, we
are not surprised when we see clearly the people, buildings, trees,
etc., beyond it, but this natural expectation is turned into the most
startled surprise when it is found that the view of these objects is not
cut off by placing a common brick between the two parts of the telescope
and directly in the apparent line of vision, as shown in the
accompanying illustration, Fig. 34.
[Illustration: Fig. 34.]
In truth, however, the observer looks _round_ the brick instead of
through it, and this he is enabled to do by means of four mirrors
ingeniously arranged as shown in the engraving. As the mirrors and the
lower connecting tube are concealed, and the upright tubes supporting
the pretended telescope, though hollow, appear to be solid, it is not
very easy for those who are not in the secret to discover the trick.