from a device which I executed in 1801, and brought before the public at
the exhibition then given, by the French government, of the produce of
national _industrie_. It was, nothing more than a _pendulum_, made with
a view to lengthen, considerably, the going of a given clock, without
altering the wheels. To that end, the weight or bob, was a heavy bar _C
D_, suspended diagonally on two points _A B_, placed at a distance from
each other, exactly equal to the length of the said bar: and _that_ by
the double cross-bars _B C_ and _A D_, of a length sufficient to make
the whole assume a form exactly square: where it may be noted--that were
this figure _longer_ than high, the curve of vibration would have two
points of inflexion, and the bar _would not_ place itself horizontally
at last; and that were it narrower and _higher_, that curve would
assume a form more like, though still distant from, the arc of a circle.
In the present case, such was the effect of this disposition of things,
that the centre of gravity of the bar described, in vibrating, a curve
_E C D F_, the lower form of which, was so near to a _horizontal line_,
that the _times_ of vibration were immensely prolonged; so much indeed,
as to represent a common pendulum of several thousand feet in height;
and to give a proportionate slowness to any mechanism with which it
should have been connected. In fact, this line is so minutely different
from such horizontal line, that it is wholly included in the thickness
of the _drawn-line_ _C D_: nor becomes visible but near it’s two ends _C
D_, when it begins to rise, and _then_ rises faster than that described
by a _short_ common pendulum.
In fine, this curve itself is formed by continually bisecting the line
or bar _C D_, and drawing lines from it’s centre of gravity, thus found
in one of it’s positions, to the same in another position, till the
curve _E C D_, &c. arises from this process.
It follows, then, from the nature of this curve, (or pair of curves)
that the time of vibration of this pendulum is the _longer_, the
_shorter_ the arcs are, in which it vibrates; and that, when the
vibrations have attained a certain _length_, compared with the height to
which the centre of gravity rises, the _time_ becomes considerably
shorter. I shall not now pursue this idea, because it is at once an
abstruse question, and at the same time one of uncertain utility--I
mean that it’s use is problematical as a pendulum: since the _time_ of a
vibration depends on it’s _length_, which cannot _easily_ be determined
by any invariable method. I shall, however, add two things on this
subject, by way of land mark; the one, that the balance-wheel of a watch
has power enough to drive this pendulum, heavy as it is;--and the other,
that I have _seen_ it make (for many hours together) vibrations of _half
a minute’s duration!_ In a word, this is one of the subjects, which
untoward circumstances have prevented me from bringing to maturity--but
which I owe to my subscribers, and the public, in any, or every state,
to which I have brought them.
I therefore, say nothing more of this Instrument as a pendulum: but an
inspection of the figure will shew, that it will not be useless as an
ELIPSOGRAPH--which it clearly is, since the intersection of the bars _A
D_ & _B C_; describes a true Ellipsis. It may be further shewn, that the
ends of the moveable bar _C D_, are the vibrating _foci_ of a second
ellipsis, like the first, which rolls under the other, so that the curve
itself is _that_ which the centre of one ellipsis _a b c_ would
describe, by rolling on the surface of another _e b d_. But, into these
considerations I cannot now enter, as my “Century of Inventions” is fast
becoming due, and time commands dispatch; I beg leave, therefore, to
pass to the relation this subject seems to bear to a “Marine Level.”
It must, however, be premised, that I scarcely expect either of these
methods to be correct enough for astronomical observations; as among
other things, they have the _nautical top_ to contend with: but if I am
fortunate enough to have suggested useful methods of procuring
_relative_ stability on board a rolling ship, so as to suspend the
better, a _nice_ instrument of astronomy; or so to counteract the
restless ocean, as to assist the victims of sea-sickness, I shall not
entirely have lost my labour.
My first idea on this subject, is the following: If we had on
ship-board, a simple pendulum of several thousand feet high, it appears
_certain_ that the oscillations of the ship would be begun and ended,
before any single vibration could have been given to such a length of
pendulum--which therefore, would scarcely vibrate at all: and if the
natural _time_ of this compound pendulum (for we are not confined to
these small dimensions) were made to be much longer than those of the
ship _on it’s meta-centre_, this pendulum would scarcely vibrate at all:
because it’s several tendencies to take motion from the ship, would
extinguish each other before they had had time to produce any common
effect.
Further, this result would probably be assisted by another property
belonging to this mechanism: see fig. 4. This diagonal suspension, as
repeated at _a b c d_, fig. 4, is of such a nature, that when it’s
centres _a b_, are placed in any oblique position _e f_, (say by the
rolling of a ship) the suspended bar _c d_, immediately takes a position
of opposite obliquity _g h_, pointing _upward_ towards _i_, just as much
as the line _e b_ points _downward_; while the middle line _k l_ remains
level--whether caused by the slides _k l_, or the single slide _m_.
I dare not assert any thing respecting the form this principle should
assume, in order to produce the most useful effects; but it appears that
the principal _weight_ of the apparatus should be placed in the centre
of gravity of the under bar _c d_. It would occur, of course, to every
mechanician applying this System to real use, that in this fig. 4, we
have only provided for one motion of the ship, the _rolling_ motion: and
that, in consequence, this System should be suspended _in_ another
similar one, acting longitudinally, so as to provide for the _pitching_
motions of the vessel. In a word, I confess, with regret, that I leave
much _to do_, by way of bringing this idea to maturity--it being at this
late hour, more than doubtful, whether I shall myself ever be able to
resume the subject _at sea_, where alone it can be duly tried.
OF
A SECOND ESSAY,
_To procure a Marine Level_.
This would seem to be a simpler process than the former: but how far it
may go beyond it in effect, I cannot say--having never had it in my
power to _try_ either of these ideas on ship-board. I therefore merely
present them to my readers, as themes for future thought and experiment.
Plate 45, fig. 5 represents this System--which is founded on the idea of
deadening oscillatory motions at sea, by connecting the bodies to be
thus _guarded_, with _a stream of flowing liquid_, the horizontal
motions of which _must be_ subject to laws very different from those
which rule vibrating bodies merely suspended.
The fluid used in this Machine (as oil, water, mercury, &c.) is to be
pumped up by appropriate mechanism, from the vessel into which it flows
at _x_, into a vessel placed a little above _z_; and to be let out by
the cock _y_, through a kind of strainer _s_, of sufficient collective
area to supply, with ease, the descending column _C_. The vessel and
tube _C D_ are made as thin and light as possible: and the upper part,
which is spherical, is inclosed in and suspended by the universal joint
_a b c_, like those used to suspend other bodies, as a compass, &c.
Moreover, the areas, at different heights, of the tube _C D_, are made
in the inverse ratio of the velocities of the spouting fluid, at each
given depth--so as to leave it but little tendency to press either
outward or inward, while thus obeying the law of gravity. By these
means, then, I think no vibrating motion will be excited in the falling
column: but that the liquid will continue to flow perpendicularly, so as
to preserve (nearly) the quietude of the vessel _C D_, and of any mirror
or instrument it may be wished to keep in a given position, by
connecting it with the perpendicular line thus obtained.
I repeat, however, that I know not how far these methods may go towards
obtaining an artificial horizon, for astronomical uses. Indeed, I fear
they will fall short in this respect--but I think them still worth
trying, even for these--but especially for the purposes to which I have
already alluded. And, if success crowns _this publication_, to the
degree I am led to anticipate, I will not always leave so rich a
question, in this doubtful predicament.
OF
A FIRE-ESCAPE,
_On a retarding Principle_.
This is a recollection from the specification of a Patent which I took
out above thirty years ago, and in which I huddled together as many
objects as a child would like to see in a box of play things. I perhaps
acted, then, according to the _words_ of a French proverb--“abondance de
bien ne nuit pas;” but in so doing, I fell into the charybdis of
_another_ French proverb--“qui trop embrasse, mal étreint,” (a wide
embrace cannot be a strong one) and in so doing, paved the way to much
litigation--which happily did not occur.
The intention of this Machine, as represented in Plate 46, fig. 2, was
to retard the fall of any _body_, or person, suspended to it, so as to
prevent any concussion on reaching the ground. The means are brought to
view in the perspective sketch given of the Machine. It is a kind of
_jack_, inclosed in a case, and supposed to be laid carefully aside in
the house represented in fig. 1 of this Plate. The Machine has a barrel,
much like that of the jacks used for roasting; round which a rope is
coiled, of sufficient length to reach the ground: and a wheel, connected
with this barrel, works in an endless screw, which turns a shaft also
like that of a common jack, but somewhat stronger; and finally, to this
shaft is fixed a small cross piece, carrying, on pins, two weights _y
z_, inclosed in the _fixed_ barrel _x_; by the centrifugal force of
which enough friction is created, to prevent the acceleration of the
falling body--whether a person or weight of any kind.
There is, moreover, a jib _a_, fig. 1, fixed between some, or all, the
windows of the house whose inhabitants it is wished to guard from the
danger of fire; this jib having the property, from the form of it’s
foot, of taking by the suspension of any weight to it, a position
perpendicular to the wall: Insomuch, that by the act of suspending the
Machine to the jib--engaging the wrist in the noose _n_, and perhaps the
foot in another loop of the same cord; a person may safely flee those
dangers from fire, of which so many persons become the unhappy victims.
Since the 46th. Plate was engraved, it has occurred to me, that a method
should have been shewn for raising the cord _n_, (fig. 2) after each
descent. This operation might be performed by a handle put on the axis
of the Machine, accompanied by a ratchet on the wheel, just like the
similar parts of a jack for roasting. But, lest the inmates of a house
on fire, should not have presence of mind enough to perform this
operation, it might be better to have a spiral spring _in_ the Machine,
to be _wound up_ by the descending body, and of force sufficient to
raise again the cord after such descent.
OF
A SECOND FIRE-ESCAPE,
_By breaking the Fall_.
This Machine is also shewn in Plate 46, at fig. 1. It consists of a
large truck, _A_, to be drawn rapidly to any _house on fire_, by one or
more horses. The carriage or frame part _B B_, is an _open_ square frame
_subtended_ by a first sheet of sack cloth, similar to the sacking of a
bed: and on this are laid five, or more, _air mattrasses_ made of sack
cloth, and varnished on the inside so as to be nearly air-tight; I say
_nearly_ so, for it is _not_ intended they should form a spring capable
of _returning_ any object thrown on them. On the contrary, each of the
mattrasses has, at one or both ends, a valve 1, 2, &c. opening
_outwards_, but kept closed by proper springs, so as to determine the
pressure at which the air shall escape; that pressure being carefully
graduated, so that the upper mattrass shall give way with ease, the
second with greater effort, and the successive ones with progressive
difficulty, until the under one remains totally closed, and stops the
falling body altogether. By these means, if enough mattrasses are used,
and they are _duly_ regulated, a person may jump from a house of three
or four stories without incurring any danger. As to the length and
breadth of this fire-escape, it should be ample enough to give the
sufferers confidence to take the leap, and as small as an easy passage
in the principal streets would require.
One thing must be described in _words_--as the mechanism to which it
relates is fixed under the truck; and could not be seen in this
perspective figure. These mattrasses are filled with air by an
_horizontal air pump_, worked by a _crank_, which the axle itself of the
hind wheels of the truck forms: whence, by pinning this axle to either
of the hind wheels, the very motion of the carriage, as drawn by the
horses, would distend the mattrasses--which would thus be ready for use
the moment they arrived on the spot; and moreover, when there, this air
could be replenished, after using, by turning this axle, through the
wheels, _by hand cranks slipped on it’s ends_ at the place of the
linch-pins. Or, in fine, this operation might be performed by an air
pump prepared for it alone, and placed in any convenient part of the
Machine.
OF
A ROTATORY CHOCOLATE MILL.
Figures 1 & 2 of Plate 47, exhibit this Machine. It is, merely, an
attempt to effect, by power and a rotatory motion, what is done by hand
and a vibrating one. To understand this latter, my readers (who have not
seen chocolate made) will suppose a metallic rolling-pin, but
cylindrical held in both hands, and moved parallel to itself, over a
slab of marble, to and from the person employed; who holds the
instrument _fast_ when pushing it from him, and suffers it to turn _a
little_ every time he draws it towards him. He thus presents, sometime
or other, every particle of the chocolate to every part of the slab and
the roller: and this is also done by the Machine shewn in Plate 47. In
figs. 1 and 2, _A_ represents a cylinder of stone or metal, used instead
of the aforesaid slab; and _B_ a cylinder answering to the roller in
question. The latter is placed, by it’s axis, on two forks _a b_, so as
to lean, by it’s weight, obliquely against the cylinder _A_, which it
does less or more heavily as the forks, or stands _a b_, are placed
nearer or farther off from the general centre. Further, the motions of
these two rollers _A_ and _B_, are connected by two equal (or nearly
equal) wheels _c d_, by which, when _A_ is turned, _B_ turns also; but
so as to give the surface of the latter _much less_ velocity than that
of _A_, though in the same direction. By these means, all the matter
adhering to both cylinders (for chocolate is made in an unctuous state)
is at one time or another, brought into intimate union, and ground
together; and thus is the usual problem resolved, on rotatory
principles: nor need we mention the several scrapers, &c. that would be
applied to gather up the paste to the middle of the rollers, when spread
abroad by the grinding process.
It may not be useless, just to say here, that this is likewise a good
mill for grinding paint or oil colours.
OF
A ROTATORY MANGLE.
I have insisted, often, on the propriety, mechanically speaking, of
doing every thing by rotatory motion; and thus of avoiding oscillation
wherever it is possible. The present Mangle is another attempt to employ
that principle. In Plate 47, figs. 3 and 4, is an under cylinder, turned
as usual by any convenient _power_. _B_ is a small cylinder not
connected with it, nor touching it, being intended merely to receive the
weight of the mangle-cylinder _D_, with the _goods_ rolled on it. _C_ is
an upper cylinder as heavy as necessary, or loaden through it’s
_journals_ or centres, with sufficient weights to make it so. Again, the
motions of the two cylinders _A_ and _C_, take place in such a
direction, that any round body placed and pressed between them, would
receive from them the same motion; and thus, a roller of goods, there
introduced, will be _mangled_. This process is so performed, because the
cylinders have toothed wheels _a_, _b_, on their axes, but which do
_not_ geer together: These wheels being connected by an intermediate
wheel _c_, which makes them concur in producing the rolling effect above
mentioned. But, one thing remains to be observed: the wheels _a b_,
though drawn apparently equal, are not equal. The upper one _a_, has a
tooth or two _more_ than the under--so that the motion to the right hand
of the under surface of that cylinder, is not equal to the opposite
motion of the cylinder _A_. And hence, the cloth roller _D_, progresses
from _D_ towards _x_, between the cylinders _A C_, and finally falls out
at _x_, after as many turns of the whole, as the wheels _A C_ have been
calculated to give; and this, is according to the degree of mangling
required.
OF
A MACHINE,
_For driving the_ SHUTTLE _of_ POWER LOOMS.
It is too late to bring this Machine into what might almost be called an
overstocked market of ingenuity--since many power Looms exist, work, and
seem to want nothing to make them perfect. But an idea of _forty years_
standing, founded on a principle worthy of attention then, may perhaps
not be altogether vain at present: Besides--I have engaged in my
prospectus to present it to the public. I could, indeed, enter into
other parts of the Power Loom--which I had then begun to execute; but
such is the rapidity with which that Machine is now _striding_ to
perfection, that it would be superfluous. I merely then, fulfil my
promise.
On the afore-mentioned occasion, I thought it of importance, that the
force employed to throw the shuttle, should be capable of being
regulated to any and every degree: and especially should be fully
_prepared_ to act, _before_ it’s action began: and should, then, act
independently of every other impulse.
In fig. 1 of Plate 48, _A_ is a wheel or pulley of about six inches in
diameter, from which two cords proceed in opposite directions (_B C_)
to the _pickers_, which drive the shuttles _D E_ in the usual method.
This pulley runs on an axis going through the bottom of the lathe, (or
beater) and it _might_ have a crank, behind, of a radius equal to _a b_:
but to shew the whole in one figure, I suppose the following mechanism
to be placed in the front of the lathe, and just _before_ the face of
this wheel or pulley _A_. _c d_ is a bar turning on the centre _c_, and
receiving at it’s other end the pressure of a spring _e d_, which in
it’s turn, is susceptible of different degrees of springiness, as
regulated by the screw _f_. On a stud _i_ in the wheel _A_, is put the
small bar _i d_, which forms also a turning joint in the bar _c d_: and
thus communicates the effort of the spring to the stud _i_, and thence
to the wheel _A_. Finally, this wheel has either under it, on the front
side of the lathe, or on it’s axis, at the back, a pulley, by which it
can be turned, by means of one or other of the cords brought from the
_breast beam_ of the loom, round the pullies _x_ and _y_, to this wheel
_a b i_, according to the dotted lines. Supposing then, _one_ of these
cords to be tightened by the backward motion of the lathe, it will draw
the wheel _A_ about half round: when the stud _i_ will rise to the point
_b_, straining the spring to get over the centre: and as soon as it _is_
over, the spring will _act_, and drive the picker and the shuttle with
the desired speed, independently of any other _mover_. And it is
evident, that now the opposite cord _x_ or _y_, will be tightened so
that when the lathe shall be again pushed backward to form the opening
for the shuttle the slide will be carried back over the centre _a_, and
re-produce another impulse in a contrary direction.
OF
AN AIR PUMP,
_Or_ ESSAY _towards completing the Vacuum_.
The rapidity with which a vacuum is formed by an Air Pump, depends on
the _ratio_ between the contents of the receiver and those of the pump
barrels. If the latter be just equal to the contents of the former,
(which is a _very_ large proportion) the exhaustion will follow this
series:--there will _remain_ in the receiver after each stroke, the
first contents being 1, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, 1/256,
&c. But if the pump barrel contains _twice_ the volume of the
receiver--then the remaining air, after the strokes, will be 1/3, 1/9,
1/27, 1/81, 1/243, 1/729, 1/2187, 1/6561, &c. being much nearer to a
vacuum than on the former supposition.
To meet this case, then, I have thought a water pump might be used: that
is, a barrel or vessel, _much_ larger than the receiver; and which by
the action of a smaller pump, placed on a lower level, might be
alternately filled with water and emptied so as in a few operations to
complete the exhaustion, very nearly.
Thus, in fig. 2 of Plate 48, _A_ is a receiver, _B_ is a large vessel
that can be filled with water from the tub _C_ below; and _D_ is the
pump, worked by the handle _E_. It is a common water pump, (so much the
readier adopted, as requiring _little_ care in the execution.) The
question was to make this pump alternately _fill_ and _empty_ the vessel
_B_. Adverting first to the _filling_, _a c_ are two cocks, having each
a side-passage for the water; and these passages are _now_ so placed, as
by working the pump we suck water out of the tub _C_, and throw it into
the vessel _B_, through the valve _b_;--by which means all its air is
driven out through the lateral valve _e_. When this is done, the cocks
_c d_ (which are so made as to be worked by the same _mover_) are turned
into a new position, which opens the pipe _p_ to the pump _D_, and
_that_ _q_ to the returning spout _r_; by which means the water is drawn
_from_ the vessel _B_, and thrown into the tub _C_: so that the air is
again drawn out of the receiver _A_, through the inverted valve _s_,
into the vessel _B_, and another degree of exhaustion occasioned. This
being done, the cocks are again put into their present position; the air
expelled by the water through the valve _e_ as before, and a new stroke
prepared. It is scarcely needful to add, that if the vessel _B_
contained ten times as much volume as the receiver _A_, the exhaustion
of the latter at each emptying of the vessel _B_ would follow this
ratio--1/11, 1/121, 1/1331, &c. thus approaching by rapid degrees to a
perfect vacuum. The water, or liquid, used for this purpose would of
course be as perfectly purged of air, as possible.
OF
AN INCLINED WATER WHEEL.
The principal mechanical merit I conceive this Machine to possess, lies
in the facility it gives of taking a stream of water as _high_, and
discharging it as _low_ as possible: and both nearly in the direction in
which it naturally flows. Of the advantage it possesses in keeping the
water a long time from falling, I shall not now speak, as it would
require more discussion than this work comports; and, moreover, the
Plate confines us to a somewhat contracted representation, which I hope
my readers will excuse.
Plate 48 fig. 3, _A B_ is the section of the wheel, and _C D_ a small
portion of it’s circumference--which shews the form and position of the
floats _a b c_, &c. _E_ is a floor on which the upper water flows, and
from which it falls thinly on to the wheel--whose motion is purposely
made as slow as possible. The water then, occupies one half of the
wheel’s circumference, falls by a gentle slope and finally leaves the
wheel at _d_, whether it there touches the lower water, or not. This
wheel is allowed to be incapable of _using_ to advantage a large stream
of water--but is doubtless fit to employ a small stream, _in the best
manner_.
OF
A VESSEL,
_To assist in taking Medicine, &c._