_Mr. Seymour and his family visit the Major at Osterly Park.--A
controversy between the Vicar and the Major.--The
sucker.--Cohesive attraction.--Pressure of the
atmosphere.--Meaning of the term suction.--Certain animals
attach themselves to rocks by a contrivance analogous to the
sucker.--The limpet.--The Walrus.--Locomotive organs of the
house-fly.--A terrible accident.--A scene in the village, in
which Dr. Doseall figures as a principal performer.--The Vicar’s
sensible remonstrance.--The density of the atmosphere at
different altitudes.--The pop-gun.--The air-gun.--An antiquarian
discussion, in which the Vicar and Major Snapwell greatly
distinguish themselves._
In the course of the ensuing week Mr. and Mrs. Seymour proceeded to
offer their congratulations to the new proprietor of Osterley Park. On
being ushered into the library, they were not a little surprised and
startled by the loud voice of the major, who, addressing Mr.
Twaddleton, exclaimed,
“Never will I again suspect the antiquity of your rarities, nor
question the rarity of your antiquities.”
“Mr. and Mrs. Seymour,” said the major, “welcome to Osterley Park. You
find me, as usual, engaged with our friend in a learned controversy,
and I begin to fear that my warmth may have offended him.”
“Offended me!” exclaimed the vicar, “oh no. No, indeed, my dear Major
Snapwell; a difference of opinion on an antiquarian subject may excite
my regret, and in some cases, as in the present instance, awaken my
pity; but it cannot offend me; it can never occasion any feeling like
anger: that would be to visit the folly of others upon myself.”
“What is the subject of your difference, gentlemen?” asked Mr. Seymour.
“The evidences of druidical rites, as deducible from certain cavities
to be found in granitic rocks, and which have received the appellation
of _rock basins_,” replied the major.
“And of which,” exclaimed Mr. Twaddleton, “I have a most unquestionable
specimen, collected by no less a geologist than the curator of the
cabinet at Penzance, from that ancient metropolis of the druids,
_Carn-bre hill_.”
“I admit,” said the major, “that I never before saw so perfect a
specimen; it is as spheroidal internally, as if it had been actually
shaped by a turning-lathe.”
“And yet, in spite of such evidence,” replied the vicar, “you question
its sacred origin, and deny its ever having been used as a pool of
lustration.”
Mr. Seymour here interposed. “Upon a subject of purely historical
difficulty, I might feel diffident in offering myself as an umpire
between such learned antiquaries; but, as the origin of ‘rock basins’
involves a geological question, I will venture to deliver an opinion.
Depend upon it, vicar, that you are maintaining a position that cannot
be defended; these uncouth cavities, together with all the fancied
statuary of Borlase(27), never been shaped by any chisel but the tooth
of time, nor have any artists but the elements been engaged in their
formation.”
“What say you to that, vicar?” triumphantly exclaimed the major.
“Oh, impiety, impiety!” cried the vicar;--
“‘Hostis habet muros, ruit alto a culmine Troja,’
as Maro has it. That such glorious monuments, which have so long braved
the tempests, should fall under the hammer of these Philistines!
Geology, Mr. Seymour, is infidelity in masquerade; remember the mites
in the Cheshire cheese, Mr. Seymour, ‘consider their ways and be wise.’”
“Philistines as we are, in your opinion,” replied his opponent, “our
forges have served to sharpen your weapons against the attacks of
infidelity.”
“Come, come, gentlemen,” said Mr. Seymour, “the continuance of this
discussion can neither amuse nor instruct us. I have, however, some
intelligence to communicate which will soothe every feeling of
irritation. We have received a letter from Isabella Villers, in answer
to an invitation to Overton, and she graciously accepts it, and
proposes being with us on Wednesday next.”
The major was delighted, and conversed upon various points connected
with the intended union of his nephew with that lady, which we do not
think it necessary to relate in this place. The vicar and major shook
hands, and it was proposed that they should dine at Overton Lodge the
following day, and, as a specific overture, that the major should visit
the vicarage in his way, and again inspect some of the disputed
antiquities of the reverend collector.
The following morning was occupied with the consideration of those
different toys which are indebted for their operation to the pressure
of the atmosphere.
“Tom,” said Mr. Seymour, “fetch hither your leathern sucker.”
“John is, at this moment, amusing himself in the garden with the one
which I brought with me from school,” replied Tom.
“Then you shall construct another for yourself. Here is leather and
string.”
“This leather is too stiff; but I may, perhaps, make it answer the
purpose by first soaking it.”
Having allowed it to remain in water for a short time, the leather
became sufficiently pliable for his purpose; he therefore cut it into a
circular shape, and affixed a string through its centre. The juvenile
party now hastened to the lawn, and having once again dipped his
newly-constructed sucker into the water, the ingenious boy placed it
upon a stone, pressed down the leather with his foot, and succeeded in
making it raise the weight.
“Well done, my boy! Now, then, explain the reason of the leather’s
adhesion to the surface, and of its being thus capable of retaining its
hold, notwithstanding the gravity of the stone.”
“In the first place,” answered Tom, “the edges of the wet leather, from
being closely pressed, stuck with sufficient firmness to the smooth
surface of the stone, to resist the force of the string as I pulled it
upwards; the consequence was, that a hollow was formed in the middle
part of the leather; and, as that hollow place cannot contain any air,
it is called a _vacuum_.”
“Very well,” replied his father, “so far you are right; but you have
not informed me in what manner a _vacuum_ acts in preventing the stone
from quitting the leather.”
“It makes it adhere to it by some kind of _suction_, but I confess that
I do not exactly understand the subject.”
“Then let us proceed cautiously and deliberately in the explanation. In
the first place, you have said, and said correctly, that the edges of
the leather adhere to the stone; but what is the nature of the power to
which this adhesion is to be referred? I perceive you are puzzled by
the question: attend, then, to my explanation: you must know that there
exists a tendency in all bodies to adhere together, provided the
contact of their surfaces be sufficiently perfect; this property is
termed _cohesion_, or cohesive attraction, from the Latin word
_cohæreo_, which I need not inform you signifies to _stick together_.
The dry leather will not adhere to a smooth surface, because, in that
case, the contact cannot be rendered sufficiently perfect; but, when
saturated with water, the interstices of the leather are filled with
that fluid, and the inequalities of the surface, which must always
prevent close contact, are removed. If two bodies, when placed
together, be not sufficiently smooth, or polished, it will be vain to
make any attempt to produce their cohesion; since the particles will,
in such a state, touch each other only in a few points; it is for this
reason that carpenters, when they intend to glue pieces of wood
together, plane the surfaces perfectly smooth, before they apply the
glue.”
Tom here acknowledged that he had not before understood the reason of
the leather’s adhesion to the stone.
“Having, then, settled this point to your satisfaction,” continued Mr.
Seymour, “let us proceed. Your idea of a _vacuum_ being formed in the
hollow part of the leather is perfectly correct: for, as you draw up
the central part by the string, the hollow thus produced must
necessarily be a _vacuum_, since the air cannot pass through the
leather to supply it; in this state, therefore, the atmosphere presses
upon the exterior of the leather, and like any other weight prevents
its rising from the stone.”
Fanny and Louisa here expressed some surprise on hearing of the weight
of the atmosphere; the former observed, that she did not feel any
pressure from it. Their father explained the reason of their not being
conscious of the weight, by informing them that their bodies contained
air, which, by its elasticity, counteracted the pressure from without;
but that, if it were possible to remove all the air which the body
contained, the pressure of the atmosphere would not be counteracted;
and the consequence would be, that we should be flattened like a
pancake by its weight, which had been ascertained by experiment to be
equal to fifteen pounds upon every square inch of surface, or, as much
as forty thousand pounds upon the body of a man of ordinary size.
“Until your explanation,” said Tom, “I really believed that the leather
adhered to the stone by some kind of _suction_, just as the back of my
hand adheres to my lips, whenever I place it to my mouth, and draw in
my breath.”
Mr. Seymour here expressed a doubt whether his son was even yet a
perfect master of the subject: he told him that there was no such
operation in nature as _suction_; that it was merely a popular term to
denote the action of the air upon a vacuum. “Your hand,” said he,
“adheres to your mouth, in consequence of your forming a vacuum within
it, by forcibly drawing in your breath, and the resistance which is
opposed to its removal arises entirely from the pressure of the
atmosphere upon it. Many are the effects which may be explained upon a
similar principle. I dare say you well remember the astonishment which
you expressed at the force with which the limpets attached themselves
to the rocks.”
“O yes, papa,” exclaimed Louisa, “I well remember, when we walked on
the sea-shore, that, on first touching the limpets, they appeared loose
and moveable, but before I had time to remove them, they fastened
themselves as firmly as though they had been a part of the rock upon
which they were fixed; how could that happen?”
Mr. Seymour replied, that these sea-insects possessed the power of
converting their whole bodies into _suckers_; and he informed them,
that many other animals were endowed with a similar faculty. He
instanced the claws of the polypus, which are furnished with many such
suckers, by means of which the animal is enabled to hold to whatever it
attaches itself, with very considerable force.
“Have you never observed,” asked Mr. Seymour, “the security and ease
with which flies frequently walk upon a smooth wall, or a pane of
glass, or even along the ceiling, with their bodies downward?”
“To be sure,” replied Tom; “but are not their legs provided with some
sticky matter, which enables them to preserve themselves from falling?”
“That is a popular error, my dear; the fact is, that their feet are
provided with little cups, or suckers, which they alternately exhaust
and fill with air; by which means they are enabled to walk in every
position, over the most slippery surfaces.(28) In like manner, the
walrus, or seal, a painting of which you may remember to have seen in
the Panorama of Spitzbergen, is capable of climbing the masses of
slippery ice with perfect security.”
At this moment, Tom’s stone fell from the sucker. Louisa enquired how
it could have happened.
“The circumstance is to be easily explained,” said her father. “The
atmosphere, by its pressure, ultimately forced its way through the
edges of the sucker; its interior, therefore, became filled with air,
and it consequently balanced the external weight, which had before
confined it.”
“I think,” said the vicar, “that Tom must now surely understand the
theory of the leathern sucker; what say you, my boy? Cannot you exclaim
with Persius, ‘_Intus_ et in _cute_ novi.’”
“Which I suppose,” observed Mr. Seymour, “you would construe, ‘Well do
I know the nature of the _cavity_, and the operation of the _leather_.’”
“Exactly,” answered the vicar.
“Then never more protest against the vice of punning, for a more
atrocious specimen of the _lusus verborum_ was never sported by the
most incorrigible Johnian: but, to your classical fancy, any object
enclosed in a Latin shrine appears as a deity.”
The vicar had just drawn up his person into a suitable attitude for
combat, and would, no doubt, have defended himself against this
unexpected attack with his usual address, had not a circumstance
occurred, which put an abrupt termination to the discourse.
“See! see!” exclaimed Louisa; “what can have happened? There is Jerry
Styles, with a crowd of villagers, running towards us in the greatest
state of agitation and alarm.”
“Jerry Styles? It is, indeed, as you say, my faithful clerk,” cried the
vicar. “Bless me,--bless me, what can have happened! Is the vicarage on
fire? Has the old roof at last tumbled into the chancel?”
“Oh, sir!--oh, my dear sir!” vociferated the terrified servant of the
church, whose blanched cheeks made his red nose appear like a volcano
burning amidst a desert of snows, “poor Tom Plank has blown the roof
off his house, and is so dreadfully wounded that it is impossible for
him to survive long, if, indeed, he is not already dead.”
“How did it happen?” exclaimed several voices.
“From a _speriment_! a _speriment_! it all came from a _flossical
speriment_!” replied the breathless clerk; “but, pray, gentlemen, come
directly to the village; for mercy’s sake, gentlemen, don’t delay a
moment.”
The vicar and Mr. Seymour instantly proceeded with the terrified Jerry
Styles towards the house of the unfortunate “planer of deals;” they had
not gone far before they met several other villagers, who informed them
that Dr. Doseall was in attendance upon the wounded man, and had
pronounced him to be in the greatest danger.
On their arrival at the house, the roof of which they at once perceived
had not suffered in the fray, they learned that Tom Plank had been
engaged in some experiments for producing a _vacuum_, in the
prosecution of his new scheme of propelling passengers through a
funnel; and that, in firing a mixture of oxygen and hydrogen gases, he
had neglected the usual precaution, and blown up his apparatus; the
stop-cock had been unceremoniously expelled through the window, and, in
its passage, had ungraciously flown in the face of its master, and left
the traces of its indignation in the form of a very slight scratch upon
his forehead; this accident, with a burn of the fingers, was the only
personal injury he had sustained.
“Come, come,” said Mr. Seymour, “no mischief has occurred, and the
accident will, I trust, teach you more caution for the future. You are
not the first adventurer who has _burned_ his _fingers_ by _bubble_
speculations, and in vain attempts to _raise the wind_.”
Dr. Doseall, however, with a countenance of stern composure, and a
portentous shake of the head, maintained that the accident was by no
means so trifling as Mr. Seymour appeared to suppose; and, in
conformity with this view of the case, he had prudently bled his
patient largely, and directed sundry mixtures and lotions, together
with a _quantum sufficit_ of laudanum, in order, as he said, “to keep
down the swelling and puffing of the head,” although there were those
present who were uncharitable enough to hint, that the _swelling_ and
_puffing_ related rather to the Doctor’s bill and character, than to
the patient’s pericranium.
After a short interval, engaged in answering the numerous enquiries of
the anxious spectators, the doctor, with an air of awful solemnity,
advanced to the sufferer, and offered him a bolus of no ordinary size;
upon the virtues of which he descanted in most touching language.
“Avaunt!” exclaimed Mr. Seymour, “do you suppose that Tom Plank has the
throat of the great dragon which the Indians believe to swallow the
moon, and thus to produce the phænomena of lunar eclipses? Away with
thy treacle and pipe-clay; there cannot be the least pretext for this
parade of remedies; I warrant you that Dame Nature, unless she be put
out of humour by your officious interference, will heal the scratch
before to-morrow’s sunrise.”
The doctor, as our readers will readily imagine, was very justly
incensed at this ex-professional interference. His first determination
was to treat the matter as a joke, and to turn the laugh against the
unmannerly intruder; but the abortive smile was strangled in its birth,
and suffused the hue of death over his visage. Never did a countenance,
in the focus of his blue window bottle, by candle-light, exhibit a more
ghastly pallor; and we can scarcely predict what might have been the
consequence, had he not instantly administered a consoling cordial to
his nostrils; for, be it known, that the doctor took snuff in the same
extravagant proportion as his patients took physic. Having by these
means recovered his self-possession, he instantly seized his cane, and
waving it with as much dignity as Jove is said to brandish his thunder,
he departed in deep dudgeon, which was betrayed by a snarl, not unlike
that of a hungry dog who is unexpectedly despoiled of a savory bone,
and by a contortion of the face, similar to that we have observed in a
child who has unfortunately mistaken Aloes for Liquorice.
No sooner had the man of wrath and phials retreated from the field of
blood, than Mr. Twaddleton advanced to the suffering artist, deeming
the moment of bodily fear as affording a favourable opportunity for an
attempt to reclaim him from the error of his ways. “Tom Plank,” said
he, in a mild tone, “hadst thou given ear to the warning voice of thy
spiritual pastor, and, instead of ridiculing his advice at the sixpenny
club, hadst, like a true Christian and worthy parishioner, given heed
unto it, thou wouldst not, at this time, have been placed in such
bodily peril. Mr. Seymour has consoled thee by his opinion; sincerely
shall I pray that his judgment may be confirmed by the result, and that
the visitation may have a salutary influence upon thy future conduct.
Quit the pursuit of these bubbles, and leave wiser men to investigate
the secrets of nature; let me exhort thee to return to thy craft, sow
where thou canst reap; we cannot have figs from thorns, nor grapes from
thistles; remember the proverb, ‘an emmet may work its heart out, but
can never make honey.’ One word more and I have done--suffer not the
artist whose profit it is to furnish thee with materials, to flatter
and cajole thee--‘the dog wags his tail, not for thee, but for thy
bread.’”
As the party left the house, they met Mrs. Seymour, with Tom and
Louisa, whose looks sufficiently testified the anxiety they had
suffered.
“Is it all over? Is he dead?” asked Mrs. Seymour.
“No, no; he is quite safe; it was an extremely slight accident,
although Doseall wished us to believe that it was likely to terminate
in some dreadful manner. The vicar thinks that it may prove the means
of driving science _out_ of Tom Plank’s head, and I intend to make it
subservient to driving it still farther _into_ ours.”
“What do you mean?” cried Tom.
“I mean that it was an extremely apposite accident for illustrating the
subject upon which we were engaged at the moment of interruption.”
“This is the second accident then,” observed Louisa, “that will have
served us in our scientific studies. What a philosopher,” continued
she, “must Dr. Doseall become, if he profit by every accident he
witnesses!”
“Knowledge, my dear girl, is not promoted by the opportunity of seeing,
but by the faculty of skilfully observing, and reflecting upon what we
see; were it otherwise, the merit of a traveller might be at once
estimated by the number of shoes he had worn out. Whenever, therefore,
you hear of a discovery having been made _by accident_, do not, on that
account, depreciate the merits of its author. It is certainly true,
that many an important truth has been brought to light from some casual
observation(29), but the dexterity with which such observation was
applied constitutes the merit of the discoverer. Well, but to show in
what manner the accident of Tom Plank bears upon the subject under
discussion:--He had ignorantly fired a quantity of oxygen and hydrogen
gases in a tin vessel; the consequence of the combustion was the
immediate formation of a _vacuum_: and what happened? Why, the pressure
of the external air, not being any longer balanced by elastic matter in
the interior of the apparatus, crushed it with violence, as any other
enormous weight might have done; and so ended the accident, which
report magnified into a most awful catastrophe.”
As the party proceeded on their way home, they continued to discourse
on the subject of the air’s pressure.
“If the atmosphere exerts so enormous a pressure, and has so much
weight,” observed Louisa, “it is strange that it should not fall down
on the earth.”
Mr. Seymour replied, “that the air was a peculiar fluid, which, from
its elastic properties, was distinguished by the term of an _elastic
fluid_, the particles of which were too far distant from each other to
exert any cohesive attraction amongst themselves.”
“But I suppose,” said Tom, “that it gravitates, or is attracted by the
earth; what then can be the reason, as Louisa says, that it does not
fall, like any other body, to the ground?”
“And so it actually does,” replied Mr. Seymour. “The lower stratum of
the atmosphere rests upon the ground, but the strata above it do not
fall, because they are supported by the particles beneath them, in the
same manner as the water at the surface of a basin is supported by that
at the bottom: the only difference in these two cases arises from the
one being an elastic, and the other an inelastic fluid; so that the air
after compression resumes its original dimensions; and since the
atmosphere, by the action of gravity, is always in a state of
compression, so is it always endeavouring to expand itself.”
“If, then, the force of gravity were diminished,” observed Louisa, “the
air would become much lighter, and I suppose that is the true reason of
its being so much less dense in the upper regions.”
“Scarcely,” replied her father. “Have you forgotten the explanation[36]
which I lately gave you, of the diminution in the weight of bodies at a
distance from the earth’s surface?”
“I recollect it perfectly,” exclaimed Tom; “and it explained to us the
reason that a marble fell from the top of a house, and from the ball of
St. Paul’s with the same velocity.”
“And yet I am quite sure,” said Louisa, “that I have lately read an
account of the air being so extremely light upon the top of a high
mountain as to affect the breath and occasion great uneasiness.”
“I do not deny the fact, my dear; I only question your explanation of
its cause. Can it not, think you, be accounted for upon some other
principle than that of the diminished force of gravity?”
Louisa was unable to suggest any other probable reason.
“The fact, then,” said her father, “is simply this; since the air is
elastic, or capable of yielding to pressure, so, of course, the lower
parts must be more dense, or in a greater state of compression than
those which are above them. In a pile of fleeces of wool, are not the
lower fleeces pressed together by the weight of the superior ones, and
do they not lie light and loose, in proportion as they approach the
uppermost fleece, which receives no external pressure, and is confined
merely by the force of its own gravity?”
“Clearly,” said Louisa.
“Well then, we will suppose, for example, that the whole column of the
atmosphere were divided into a hundred parts, and that each of these
parts weighed an ounce; would not the earth, and all things on its
surface, be, in such a case, pressed upon with the whole hundred
ounces?”
“No one can deny that,” said Tom.
“The lowest stratum of air,” continued Mr. Seymour, “would be pressed
upon by the ninety-nine ounces above it; the next by ninety-eight; and
so on, until we arrived at the ninety-ninth stratum from the bottom,
which would, of course, be subjected to no more than one ounce of
pressure, or to the weight of the last and highest stratum.”
The children were perfectly satisfied with this simple explanation; and
Tom enquired whether, for the same reason, the water at the bottom of
the sea must not be very dense, and unlike that we are accustomed to
observe on the surface: his father, however, corrected this notion, by
stating that water, not being, like air, elastic and compressible,
would not suffer any material diminution in volume, although pressed
even by the enormous weight of the superincumbent ocean.(30)
“I have before alluded to the relative compressibility of air and
water, and the present appears a good opportunity for proving the fact
by an amusing experiment. See! here are the ‘_Bottle Imps_,’ vicar,
which you may remember I promised to introduce to your respectful
notice,” said Mr. Seymour. “In this jar of water, carefully closed, as
you may perceive, by parchment, are two little enamelled figures, which
shall be made to rise and fall, by alternately pressing upon and
removing the hand from the cover: thus.”
[Illustration: Two devil-like figures within an upturned bottle
bouncing about.]
“Why, the spirit of Simon Magus must surely possess thee!” exclaimed
the vicar.
The children, as may be readily imagined, were much astonished at so
singular an effect, and expressed much anxiety to be informed by what
mechanism it was produced. Their father accordingly proceeded with the
following explanation.
“I have here,” said he, “a figure exactly similar to those in the
bottle, which we will now examine. You will observe, that in its centre
there is a cavity terminating in a small orifice in the lower part;
this cavity may be made to contain any quantity of air, so as to give
the required buoyancy to the figure: now mark!--I press my hand upon
the parchment cover, and the figure, you perceive, descends; I now
remove the pressure, and see, it immediately reascends. The water in
the bottle, as I have told you, is incompressible; when, therefore, I
press upon the surface, it rises into the interior of the figure, and,
consequently, by compressing the air into a less space, renders it less
buoyant; but no sooner is the hand removed, than the enclosed air
resumes its former volume, and expels the intruding water; in
consequence of which the figure regains its former lightness, and
reascends. Do you understand me?” asked Mr. Seymour.
“Perfectly,” said Tom, “and many thanks for the explanation;” and in
this opinion did the whole party concur.
“Well, then,” continued Mr. Seymour, “you will now understand the use
of the air-bladder in fish, for it is constructed upon a precisely
similar principle. When the fish desires to descend, it presses upon
the bladder by means of its muscles, and thus condenses the included
air into a smaller volume.”[37]
“I now also perceive why the water at the bottom of the sea cannot be
much more dense than that on the surface; but, if we could dig a pit to
the centre of the earth, the air, in that case, would be highly dense,
because, unlike water, it is compressible,” said Tom.
“The density of the air,” replied his father, “would, undoubtedly,
materially increase as we descended. It has been calculated that, at
the distance of thirty miles below the surface, the air would have the
same density as water; and, at the depth of forty-two miles, that of
quicksilver; while, at the centre, it would be more solid than any
substance of which we have any idea, for its density would be thousands
of millions of times greater than that of mercury.”
Mr. Seymour then informed his young pupils, that after the lesson they
had just received, they would never again be puzzled by the motions of
the barometer, which had so often excited their wonder.
“As the quicksilver is contained in a closed tube, I do not exactly
understand how the air can act upon it; and if the tube were not
closed, it would of course run out from its weight,” observed Louisa.
“You are altogether in error,” said her father. “In the first place,”
he continued, “I will show you that the bulb at the lower extremity of
the tube is open, in order that the quicksilver may freely communicate
with the atmosphere, upon which, indeed, its action entirely depends;
while the upper space is a perfect vacuum, so as to obviate any
counteracting pressure. As to the quicksilver running out, have you so
soon forgotten that the air presses upon every body on the surface of
the earth, in the proportion of about fifteen pounds upon every square
inch? Now it is from this circumstance that the column of quicksilver
is sustained in the tube, the ascent and descent of which thus
indicates the varying pressure of the atmosphere; so that, when the
barometer falls, we know the air presses less heavily upon the earth,
and the contrary when it rises.”
“That I understand: but what can cause the pressure of the air to vary
at different times?” asked Tom.
“Cannot you imagine the atmosphere to be an airy ocean, and to be
therefore thrown into enormous waves, so that we may sometimes have a
longer column of air above us than at other times; this is one
explanation, there may be other causes not so intelligible,” answered
Mr. Seymour. “But enough of this for the present. Now, before we quit
the subject of the air’s elasticity, let us consider the philosophy of
the _pop-gun_; an amusement with which, I have no doubt, you are well
acquainted.”
“Indeed I am, papa; but do you allude to the quill, or to the wooden
pop-gun?”
“The principle in both is the same; tell me, therefore, the origin and
nature of the force which enables you to shoot your pellet to so
considerable a distance.”
“It depends upon the action of the air,” replied Tom.
“Undoubtedly: but your answer is too general; I wished you to state, in
precise terms, the changes which the air undergoes upon this occasion.
You first ram in your pellet to the further end of the tube, do you
not?”
“To be sure; and then I drive in a second pellet, and on forcing this
forward, the first flies out with prodigious force.”
“Very well: now examine what takes place; on propelling forward your
second pellet, you condense the air which is enclosed between the two,
until its elastic force becomes so great as to overcome the friction of
the first pellet; thus released, the air expands with considerable
force, and imparts a rapid motion to the pellet.”
“I have frequently heard of the air-gun,” said Louisa; “I suppose it
depends upon a similar principle.”
“It does; and it affords a very striking example of the surprising
force which air is capable of exerting, when condensed to a
considerable degree; for, by means of this instrument, bullets may be
propelled with a force very nearly equal to that of gunpowder.”
“It is a curious fact,” observed the vicar, “that although the air-pump
is a modern invention, yet the air-gun, which is so nearly allied to it
in the construction of its valves and condensing syringe, should have
existed long antecedent to it; for it is recorded that an air-gun was
made for Henry IV. by Marin, of Lisieux, in Normandy, as early as 1408;
and another was preserved in the armoury at Schmetau, bearing the date
of 1474.”
“But the air-gun of the present day,” said Mr. Seymour, “is very
different from that which was formerly made, and which, like the
pop-gun, discharged but one bullet, and that after a long and tedious
process of condensation, while it is now made to discharge five or six
without any visible variation of force, and will even act upon a dozen,
but with less effect.”
“I feel very curious to learn something more about this air-gun,” said
Tom.
“There is a reservoir for the condensed air,” replied Mr. Seymour,
“which is secured by a nicely constructed valve, and which is made to
open by pulling the trigger of the gun, so that a portion only of the
air is disengaged, which, rushing into the barrel, gives motion to the
ball.”
“But how is the condensed air introduced into the reservoir?” asked Tom.
“By means of a condensing syringe,” replied his father; “but I will
take an opportunity of exhibiting the instrument in operation.”
The reader will be pleased to recollect that the major agreed to pay a
passing visit to the vicarage; it now becomes our duty to record what
happened upon that memorable occasion; and we, perhaps, cannot better
represent the nature of the discussion that took place than by relating
the account as it was given by the belligerent parties themselves in
conversation with Mr. Seymour.
“Well, gentlemen,” said Mr. Seymour, “is it peace or war? I trust you
have amicably adjusted all your differences.”
“Upon my word,” answered the vicar, “I have just reason to complain of
the major’s unjustifiable scepticism upon points that are perfectly
unquestionable.”
“You continue then to smart under the major’s stinging criticisms,
‘_majore sub hoste_.’ There is a Latin pun for your consolation,” said
Mr. Seymour.
“The vicar alludes, I suppose,” said the major, “to the doubt I
expressed respecting the authenticity of his leathern money?”
“That is one of the many subjects upon which, I must say, you have
betrayed a deficiency in historical knowledge. Seneca informs us that
there was anciently stamped money of leather; and the same thing was
put in practice by Frederick II. at the siege of Milan; to say nothing
of an old tradition amongst ourselves, that, in the confused times of
the barons’ wars, the same expedient was practised in England.”
“You strangely mistake me,” replied the major; “I never questioned the
truth of these historical statements; I know full well that numerous
substances have, at different times, and in different countries, been
adopted in exchange, as conventional representatives of property. I
have already stated that cattle were employed as the earliest measure
of value (31). We find, for instance, in Homer, that the golden armour
of Glaucus was valued at a hundred, and that of Diomedes, at ten oxen.
Among the Indians, _cowries_, or small shells, are used; and the
Abyssinians employ salt, bricks, and beads for this very purpose; the
ancient Britons are said to have circulated iron rings as money. The
Hollanders, we know, coined great quantities of pasteboard in the year
1754; and Numa Pompilius certainly made money both of wood and leather.”
“And yet you doubt the authenticity of my leathern money, which I am
fully persuaded was coined in 1360, by John, king of France, who,
having agreed to pay our Edward the Third the sum of 3,000,000 golden
crowns for his ransom, was so reduced as to be compelled to a coinage
of leather for the discharge of his household expenses.”
“I have only questioned the authenticity of that specimen which I saw
in your cabinet,” replied the major: “and so must any person who views
it through a medium unclouded by prejudice. I will stake my whole
library to a horn-book, that our friend Mr. Seymour will agree with me
in pronouncing it a fragment of the heel of an old shoe: let him
observe the perforation, and say, if he can, that it has not been
produced by a nail or peg. But really, my dear Mr. Twaddleton, you have
forced me, much against my inclination, into this controversy.”
“Very good, sir! very good! the heel of an old shoe, forsooth! But I
thank you, Major Snapwell,” exclaimed the vicar with some warmth; “I
thank you, sir. Your assertion, while it evinces your own want of
historical information, establishes, beyond doubt, the authenticity of
my treasure, and the triumph of my opinion.”
“Assuredly,” said Mr. Seymour, with a wicked smile; “I dare say there
may be numerous holes in this leathern coin; for many have been the
antiquaries who have, doubtless, _pinned_ their faith upon it.”
“Psha, psha!” cried the vicar; “for once, at least, Mr. Seymour, let me
entreat you to be serious; the subject, sir, is important, and merits
your respect. It is from that very hole that I am enabled to identify
the coin: yes, major, from that very hole, which you affect to despise,
I am enabled to derive its principal claim to antiquity. Are we not
expressly informed, that the leathern money of John of France had a
little nail of silver driven into it?”
“Well, then,” continued the major, “what say you to that tell-tale
stitch, which I so unfortunately picked out with my penknife?”
“Admirable ingenuity! most refined sophistry! provoking perversion!”
exclaimed the vicar. “It is really amusing to observe the address with
which the prejudiced observer distorts every fact to his own advantage.
Why, bless me, sir, that stitch is strong enough to drag fifty such
opponents out of the slough of unbelief.”
“Do explain yourself,” said Mr. Seymour.
“Explain myself! the stitch speaks for itself, sir. Were not these
leathern coins strung together in different numbers, to facilitate
payments? For, you will admit, that it would have been extremely
inconvenient to have coined single pieces of leather, of different
denominations. But stop, sir, stop; look at this, look at it, major,
with care and attention. That,” said the vicar, as he drew a small coin
out of his waistcoat pocket with an air of imperturbable gravity and
self-satisfaction, “is a current halfpenny, in lead, of James II; and
if your eyes are not hoodwinked by prejudice, you may probably perceive
a piece of copper in its centre, which, we are told, was thus
introduced for the purpose of rendering the currency lawful.”
The dinner was announced before the conclusion of the discussion; and
as the reader will probably agree with us in thinking that a question
of such grave historical importance ought not to be decided without due
care and deliberation, we shall afford the disputants a reasonable time
for reflection, and put an end to the chapter.
-----
Footnote 36:
See page 28.
Footnote 37:
In the cod-fish the air bladder is familiarly called the _sound_.
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[Illustration: Two boys blowing bubbles from tobacco-pipes.]