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upper edge of the lath was an inch below the surface, the rip-
ples could be produced. When the vessel had a glass bottom,
the luminous figures produced by a light beneath and a screen
above, were very beautiful (96). Glass, metal and other plates
could thus be easily experimented with.

118. These ripple-like stationary undulations are perfectly
analogous as to cause, arrangement and action with the heaps
and crispations already explained, i. e. they are the results of

2 A

354 On the Forms and States of Fluids [ 1 83 1 .

that vibrating motion in directions perpendicular to the force
applied (105), by which the water can most readily accommo-
date itself to rapid, regular, and alternating changes in bulk in
the immediate neighbourhood of the oscillating parts.

119. From this view of the effect it was evident that similar
phenomena would be produced if a substance were made to
vibrate in contact with and normally to the surface of a fluid,
or indeed in any other direction. A lath was therefore fixed
horizontally in a vice by one end, so that the other could vibrate
vertically ; a cork was cemented to the under surface of the
free end, and a basin of water placed beneath with its surface
just touching the cork ; on vi- Y\%. 29.

brating the lath by means of the
glass rod andfingers(6T), a beau-
tiful and regular star of ridges
two, three, or even four inches
in length, was formed round
the cork, fig. 29. These ridges
were more or less numerous ac-
cording to the number of vibrations, &c. As the water was
raised, and more of the cylinder immersed, the ridges dimi-
ished in strength, and at last disappeared : when the cylinder
of cork just touched the surface, they were most powerfully
developed. This is a necessary consequence of the dependence
of the ridges upon the portion of water which is vertically dis-
placed and restored at each vibration. When that, being par-
tial in relation to the whole surface, is at or near the surface,
the ridges are freely formed in the immediate vicinity ; when
at a greater depth (being always at the bottom of the cork),
the displacement is diffused over a larger mass and surface,
each particle moves through less space and with less velocity,
and consequently the vibrations must be stronger or the ridges
be weaker or disappear altogether. The refraction of a light
through this star produces a very beautiful figure on a screen.
120. A heavy tuning-fork vibrating, but not too strongly, if
placed with the end of one limb either vertical, inclined, or in
any other position, just touching the surface of water, ink,
milk, &c. (75), shows the effect very well for a moment. It
also shows the ridges on mercury, but the motion and resistance
of so dense a body quickly bring the fork to rest. It formed

1831.] on Vibrating Elastic Surfaces. 355

ridges in hot oil, but not in cokl oil (76). With cold oil a very
inclined fork produced a curious pump-like action, throwing up
four streams, easily explained when witnessed, but not so closely
connected with the present phenomena as to require more notice

121. There is a well-known effect ot crispation produced
when a large glass full of water is made to sound by passing
the wet ringer round the edges. The glass divides into four
vibrating parts opposite to which the crispations are strongest,
and there are four nodal points considered in relation to a hori-
zontal section, at equal distances from each other, the finger
always touching at one of them. If the vessel is a large glass
jar, and soft sounds are produced, the surface of the water
exhibits the ridges at the centres of vibration ; as the sound is
rendered louder, these extend all round the glass, and at last
break up at the centres of vibration into irregular crispations ;
but both the ridges and crispations are effects of the kind already
described, and require no further explanation.

122. There are some other effects, one of which I wish here
briefly to notice, as connected more or less with the vibratory
phenomena that have been described. If, during a strong
steady wind, a smooth flat sandy shore, with enough water on
it, either from the receding tide or from the shingles above, to
cover it thoroughly, but not to form waves, be observed in a
place where the wind is not broken by pits or stones, stationary
undulations will be seen over the whole of the wet surface,
forming ridges like those already described, and each several
inches long. These are not waves of the ordinary kind ; they
are accurately parallel to the course of the wind 5 they are of
uniform width whatever the extent of surface, varying in width
only as the force of the wind and the depth of the stratum of
water vary. They may be seen at the windward side of the
pools on the sand, but break up so soon as waves appear. If
the waves be quelled by putting some oil on the water to wind-
ward, these ripples then appear on those parts. They are often
seen (but so confused that their nature could not be gathered
from such observations) on pavements, roads, and roofs when
sudden gusts of wind occur with rain. The character of
these ripples, and their identity with stationary undulations,
may be ascertained by exerting the eye and the mind to resolve


356 On the Forms and States of Fluids [ 1 S3 1 .

them into two series of ordinary advancing waves moving
directly across the course of the wind in opposite directions.
But as such series could not be caused by the wind exerted in
a manner similar to that by which ordinary waves are produced
(the direction being entirely opposed to such an idea), I think
the effect is due to the water acquiring an oscillatory condition
similar to those described, probably influenced in some way by
the elastic nature of the air itself (124) and analogous to the
vibration of the strings of the ^olian harp, or even to the
vibration of the columns of air in the organ-pipe and other
instruments with embouchures.

These ridges were strong enough to arrange the sand beneath,
where ordinary waves had not been powerful enough to give
form to the surface.

123. All the phenomena as yet described are such as take
place at the surfaces of those fluids in common language con-
sidered as inelastic, and in which the elasticity they possess
performs no necessary part ; nor is it possible that they could
be produced within their mass. But on extending the reasoning,
it does not seem at all improbable that analogous effects should
take place in gases and vapour, their elasticity supplying that
condition necessary for vibration which in liquids is found in
an abrupt termination of the mass by an unconfined surface.

124. If this be so, then a plate vibrating in the atmosphere
may have the air immediately in contact with it separated into
numerous portions, forming two alternating sets like the heaps
described (95) ; the one denser, and the other rarer than the
ordinary atmosphere; these sets alternating with each other
by their alternate expansion and condensation with each vibra-
tion of the plate.

125. With the hope of discovering some effect of this kind,
a flat circular tin plate had a raised edge of tin three quarters
of an inch high fixed on all round, and the plate was then
attached to a lath (69), a little lycopodium put on to it, and
vibrated powerfully, so that the powder should form a mere
cloud in the air, which, in consequence of the raised edge and
the equal velocity (70) of all parts of the plate, had no tendency
to collect. It was seen immediately that in place of a uniform
cloud a misty honeycomb appearance was produced, the whole
being in a quivering condition ; and on exerting the attention to

1831.] on Vibrating Elastic Surfaces. 357

perceive waves travelling as it were across the cloud in opposite
directions, they could be most distinctly traced. This is
exactly the appearance that would be produced by a dusty
atmosphere lying upon the surface of a plate and divided into
a number of alternate portions rapidly expanding and contracting

126. The spaces were very many times too small to repre-
sent the interval through which the air by its elasticity would
vibrate laterally once for two vibrations of the plate, in analogy
with the phenomena of liquids ; and this forms a strong ob-
jection to its being an effect of that kind. But it does not seem
impossible that the air may have vibrated in subdivisions like
a string or a long column of air ; and the air itself also being
laden with particles of lycopodium would have its motions ren-
dered more sluggish thereby. I have not had time to extend
these experiments, but it is probable that a few, well-chosen,
would decide at once whether these appearances of the particles
in the air are due to real lateral vibrations of the atmosphere,
or merely to the direct action of the vibrating plate upon the

127. If the atmosphere vibrates laterally in the manner sup-
posed, the effect is probably not limited to the immediate vicinity
of the plate, but extends to some distance. The vertical plates
intersecting the surface of water and vibrating in a horizontal
plane (117) produced ripples proceeding directly out from them
five or six inches long ; whilst the waves parallel to the vibrating
plate were hardly sensible ; and something analogous to this
may take place in the atmosphere. If so, it would seem likely that
these vibrations occurring conjointly with those producing
sound, would have an important influence upon its production
and qualities, upon its apparent direction, and many other of
its phenomena.

128. Then by analogy these views extend to the undulatory
theory of light, and especially to that theory as modified by
M. Fresnel. That philosopher, in his profound investigations
of the phenomena of light, especially when polarized, has con-
ceived it necessary to admit that the vibrations of the ether
take place transversely to the ray of light, or to the direction
of the wave causing its phenomena. " In fact we may conceive
direct light to be an assemblage, or rather a rapid succession,

358 On holding the Breath for a lengthened Period. [1833.

of an infinity of systems of waves polarized (i. e. vibrating
transversely) in all azimuths, and so, that there is as much
polarized light in any one plane as in a plane perpendicular to
it." Herschel says that Fresnel supposes the eye to be
affected only by such vibrating motions of the etherial mole-
cules as are performed in planes perpendicular to the direction
of the rays. Now the effects in question seem to indicate how
the direct vibration of the luminous body may communicate
transversal vibration in every azimuth to the molecules of
the ether, and so account for that condition of it which is
required to explain the phenomena.

129. When the star of ridges formed by a vibrating cylinder
(119) upon the surface of water is witnessed instead of the
series of circular waves that might be expected, it seems like
the instant production of the phenomena of radiation by means
of vibratory action. Whether the contiguous rarefied and con-
densed portions which I have supposed in air, gases, vapour
and the ether, are arranged radially like the ridges in the
experiment just quoted, or whether rare and dense alternate
in the direction of the radii as well as laterally, is a question
which may perhaps deserve investigation by experiment or

Royal Institution, July 30th, 1831.

Notice of a Means of preparing the Organs of Respiration,
so as considerably to extend the Time of holding the Breath ;
with Remarks on its Application in Cases in which it is
required to enter an irrespirable Atmosphere, and on the
Precautions necessary to be observed in such Cases*.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN, There are many facts which present themselves
to observant men, which, though seen by them to be cu-
rious, interesting, and new to the world, are not considered
worthy of distinct publication. I have often felt this conclu-
sion to be objectionable, and am convinced that it is better to
publish such facts, and even known facts under new forms, pro*
vided it be done briefly, clearly, and with no mere pretension
* Philosophical Magazine, 1833, vol. iii. p. 241.

1833.] On holding the Breath for a lengthened Period. 359

than the phenomena fairly deserve. It is this feeling which
makes me send for your acceptance or rejection an account of
an effect, new to me, and to all to whom I have mentioned it,
and which seems to have some valuable applications.

At one of the scientific meetings at the apartments of His
Royal Highness the President of the Royal Society, whilst
speaking of certain men who, by means of peculiar apparatus
for breathing, could walk about at the bottom of waters, and
also of the pearl fishers, Sir Graves C. Haughton described to
me an observation he had made, by the application of which a
man could hold his breath about twice as long as under ordinary
circumstances. It is as follows : If a person inspire deeply,
he will be able immediately after to hold breath for a time,
varying with his health, and also very much with the state of
exertion or repose in which he may be at the instant. A man,
during an active walk, may not be able to cease from breathing
for more than half a minute, who, after a period of rest on a
chair or in bed, may refrain for a minute or a minute and a half,
oreven two minutes. But if that person will prepare himself
by breathing in a manner deep, hard and quick (as he would
naturally do after running), and, ceasing that operation with his
lungs full of air, will then hold his breath as long as he is able,
he will find that the time during which he can remain without
breathing will be double, or even more than double the former,
other circumstances being the same. I hope that I have here
stated Sir Graves C. Haughton's communication to me correctly ;
at all events, whilst confirming his observation by personal
experience, I found the results to be as above.

Whilst thus preparing myself, I always find that certain
feelings come on, resembling in a slight degree those produced
by breathing a small dose of nitrous oxide ; slight dizziness
and confusion in the head are at last produced ; but on ceasing
to breathe, the feeling gradually goes off, no inconvenience
results from it either at the time or afterwards, and I can hold
my breath comfortably for a minute and a quarter, or a minute
and a half, walking briskly about in the mean time.

Now this effect may be rendered exceedingly valuable.
There are many occasions on which a person who can hold
breath for a minute or two minutes, might save the life of
another. If, in a brewer's fermenting vat, or an opened cess-

360 On holding the Breath for a lengthened Period. [1833.

pool, one man sinks senseless and helpless, from breathing the
unsuspected noxious atmosphere within, another man of cool
mind would by means of this mode of preparation, which re-
quires nothing but what is always at hand, have abundant
time, in most cases, to descend by the ladder or the bucket,
and rescue the sufferer without any risk on his own part. If
a chamber were on fire, the difference in the help which could
be given to any one within it by a person thus prepared, and
another who goes in, perhaps, with lungs partially exhausted,
and who, if he inhale any portion of the empyreumatic vapours
of the atmosphere, is stimulated to inspire more rapidly, and
is therefore urged to instant retreat into fresh air, is so great,
that no one who has noticed what can be done in a minute or
in two minutes of time can doubt the value of the preparation
under such circumstances, even though from want of practice
and from hurry and alarm it may be very imperfectly made.
In cases of drowning, also, a diver may find his powers of
giving aid wonderfully increased by taking advantage of Sir
Graves Haughton's fact.

I have myself had occasion to go more than once or twice
into places with atmospheres rendered bad by carbonic acid,
sulphuretted hydrogen or combustion ; and I feel how much I
should have valued at such times the knowledge of the fact
above stated. Hoping, therefore, that it may be useful, I will
add one or two precautions to be borne in mind by those who
desire to apply it.

Avoid all unnecessary action ; for activity exhausts the air
in the lungs of its vital principle more quickly, and charges it
with bad matter. Go collectedly, coolly and quietly to the spot
where help is required : do no more than is needful, leaving
what can be done by those who are in a safe atmosphere (as
the hauling up of a senseless body, for example,) for them to

Take the precautions usual in cases of danger in addition to
the one now recommended. Thus, in a case of choke-damp,
as in a brewer's vat, hold the head as high as may be ; in a
case of fire in a room, keep it as low down as possible.

If a rope is at hand, by all means let it be fastened to the
person who is giving help, that he may be succoured if he
should venture too far. It is astonishing how many deaths

1833.] On holding the Breath for a lengthened Period. 361

happen in succession in cesspools, and similar cases, for want
of this precaution.

It is hardly needful to say, do not try to breathe the air of
the place where help is required. Yet many persons fall in
consequence of forgetting this precaution. If the temptation
to breathe be at all given way to, the necessity increases, and
the helper himself is greatly endangered. Resist the tendency,
and retreat in time.

Be careful to commence giving aid with the lungs full of air,
not empty. It may seem folly to urge this precaution, but I
have found so many persons who, on trying the experiment on
which the whole is based, have concluded the preparation by
closing the mouth and nostrils after an expiration, that I am
sure the precaution requires to be borne in mind.

I have thought it quite needless to refer to the manner in
which the preparation enables a person to increase so con-
siderably the time during which he may suspend the operation
of breathing. It consists, of course, chiefly in laying up for
the time, in the cells of the lungs, a store of that vital principle
which is so essential to life. Those who are not aware of the
state of the air in the lungs during ordinary respiration, and
its great difference from that of the atmosphere, may obtain a
clearer notion from the following experiment. Fill a pint or
quart jar with water over the pneumatic trough, and with a
piece of tube and a forced expiration throw the air from the
lungs in their ordinary state into the jar ; it will be found that
a lighted taper put into that air will be immediately extinguished.

A very curious fact connected with the time of holding the
breath was observed by Mr. Brunei, jun., and has, I think,
never been published. After the river had broken into the
tunnel at Rotherhithe, Mr. Brunei descended with a companion
(Mr. Gravatt, I think,) in a diving-bell, to examine the place :
at the depth of about 30 feet of water, the bell touched the
bottom of the river, and was over the hole ; covering it, but too
large to pass into it. Mr. Brunei, after attaching a rope to
himself, inspired deeply, and sunk, or was lowered through
the water, in the hole, that he might feel the frames with his
feet, and gain further knowledge, if possible, of the nature of
the leak. He remained so long beneath without giving any
signal, that his companion, alarmed, drew him up before he

362 On the Ventilation of Lighthouse Lamps. [1843.

desired ; and then it was found that either of them could remain
about twice as long under water, going into it from the diving-
bell at that depth, as they could under ordinary circumstances.
This was supposed to be accounted for, at the time, by the
circumstance that at the depth of 30 feet the atmosphere was
of double pressure, and that the lungs, therefore, held twice
as much air as they could do under common circumstances.
It is, however, quite evident that another advantageous cir-
cumstance must have occurred, and that the air in the lungs
was also better in quality than it would have been at the sur-
face of the river, as well as denser ; for supposing the deterio-
ration by breathing to continue the same for the same time, it
is clear that every inspiration passed into the lungs twice as
much pure air as would have entered under common circum-
stances : the injured air must, therefore, have been removed more
rapidly, and the quality of that at any one time in the lungs
must have risen in consequence. When to this is added the
effect of double quantity, it fully accounts for the increased time
of holding the breath ; and had the effect of the mode of pre-
paration now described been also added, it is probable that the
time would have appeared astonishingly increased.

I am, Gentlemen, yours, &c.,

On the Ventilation of Lighthouse Lamps ; the points necessary
to be observed, and the manner in which these have been or
may be attained*.

THE author states that the fuel used in lighthouses for the
production of light is almost universally oil, burnt in lamps of
the Argand or Fresnel construction ; and from the nature and
use of the buildings, it very often happens that a large quan-
tity of oil is burnt in a short time, in a small chamber exposed
to low temperature from without, the principal walls of the
chamber being only the glass through which the light shines ;
and that these chambers being in very exposed situations, it is
essential that the air within should not be subject to winds or
partial draughts, which might interfere with the steady burning
of the lamps.

* Proceedings of the Institution of Civil Engineers, June 2/, 1843, p. 206.

1843.] On the Ventilation of Lighthouse Lamps. 363

If the chamber or lantern be not perfectly ventilated, the sub-
stances produced by combustion are diffused through the air,
so that in winter or damp weather the water condenses on the
cold glass windows, which, if the light be a fixed one, greatly
impairs its brilliancy and efficiency, or, if the light be a revolving
one, tends to confound the bright and dark periods together.
The extent to which this may go, may be conceived, when it
is considered that some lighthouses burn as much as twenty,
or more, pints of oil in one winter's night, in a space of 12 or
14 feet diameter, and from 8 to 10 feet high, and that each pint
of oil produces more than a pint of water ; or, from this fact,
that the ice on the glass within, derived from this source, has
been found in some instances an eighth, and even a sixth of an
inch in thickness, and required to be scraped off with knives.

The carbonic acid makes the air unwholesome, but it is easily
removed by any arrangement which carries off the water as
vapour. One pound of oil in combustion produces about 1*06
pound of water and 2'86 pounds of carbonic acid.

The author's plan is to ventilate the lamps themselves by fit
flues, and then the air inside the lantern will always be as pure
as the external air, yet with closed doors and windows, a calm
lantern, and a bright glass.

In lighthouses there are certain conditions to which the
ventilating arrangement must itself submit, and if these are not
conformed with, the plan would be discarded, however perfect
its own particular effect might be. These conditions are chiefly,
that it should not alter the burning of the oil, or charring of
the wicks, that it should not interfere with the cleaning,
trimming, and practice of the lamps and reflectors, that it
should not obstruct the light from the reflectors, that it should
not, in any sudden gust or tempest, cause a downward blast or
impulse on the flame of the lamp, that, if thrown out of action
suddenly, it should not alter the burning ; and, added to these,
that it should perform its own ventilating functions perfectly.

Lighthouses have either one large central lamp, the outer
wick of which is sometimes 3| inches in diameter, or many single
Argand burners, each with its own parabolic reflector. The
former is a fixed lamp ; the latter are frequently in motion.
The former requires the simplest ventilating system, which
may be thus described :

364 On the Ventilation of Lighthouse Lamps. [1843.

The ventilating pipe or chimney is a copper tube, 4 inches in
diameter, not, however, in one length, but divided into three
or four pieces : the lower end of each of these pieces, for about
1^ inch, is opened out into a conical form about 5^ inches in

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