Transcriber’s Notes:
Italics have been transcribed as _italics_, small capitals as ALL
CAPITALS, superscripts as ^{text}.
Depending on the hard- and software used to read this text, not all
characters may display properly or at all. The alignment of the tables
may depend on the font used.
More Transcriber’s Notes may be found at the end of this text.
A NEW
CENTURY OF INVENTIONS,
BEING
Designs & Descriptions
OF
ONE HUNDRED MACHINES,
RELATING TO
_ARTS, MANUFACTURES, & DOMESTIC LIFE_.
By JAMES WHITE, CIVIL ENGINEER.
Connoissons le principe--
Nourrissons nous des Elemens.
Girard Syn. fr.
Manchester:
PRINTED FOR THE AUTHOR, BY LEECH AND CHEETHAM, WRIGHT’S-COURT,
MARKET-STREET.
AND SOLD BY
W. AND W. CLARKE, MARKET-PLACE; E. THOMSON, MARKET-STREET;
T. SOWLER, ST. ANN’S-SQUARE, MANCHESTER.
G. WILSON, 49, ESSEX-STREET, STRAND; LONGMAN, HURST, REES, ORME,
AND BROWN, PATERNOSTER-ROW, LONDON.
AND BY THE PRINCIPAL BOOKSELLERS IN THE UNITED KINGDOM.
1822.
Entered at Stationers’ Hall.
PREFACE.
It has been my lot, during a long and eventful passage through life, to
have my attention forcibly drawn to a multitude of Mechanical Subjects;
the present review of which permits me to hope, that in making them
publicly known, I should render an important service to the Arts and to
Society. But the manner of doing this has been so long a question with
me, that I have sometimes feared my ability would be extinct before I
could do it at all. The reasons, however, that urge me to make the
attempt acquire strength with the lapse of time: and whenever my
declining health bespeaks the approach of that “night in which no man
can work,” I feel deep regret, that this tribute should not have been
thrown into the treasury of human knowledge while yet, by the favour of
a good Providence, the means of doing it were more fully at my disposal.
I have determined therefore to publish these Inventions. Not because
they have been matured into a regular System of Mechanical truth; but
because they consist of _many_ distinct objects of immediate
application:--coupled with _some_ ideas of a more comprehensive nature,
that may probably extend the usefulness of this admirable study, in the
hands of Artists yet unborn.
The form, or rather the title of this work, has but one example, that of
the illustrious Marquis of Worcester; whose name may, perhaps, prolong
the remembrance of mine: an event the rightful anticipation of which, I
confess, would give me pleasure. Not that I either covet or regard what
is commonly called popular applause: but the approbation of the wise and
good I do regard, and aspire to obtain; since that alone seems to fulfil
the adage--“Vox populi vox dei.”
On the subject of our respective Inventions, my views are somewhat
different from those of the Noble Marquis; whose description of his
labours, as the custom then was, seems chiefly calculated to excite the
desire of knowing them better: whereas my wish is to infuse, at once,
the knowledge of my subjects into every head capable of receiving it.
This Work then, treats less of Theory than Practice. What are called
Principles in Mechanics, are, and must be, founded on numerous
suppositions; to present which to “the mind’s eye” requires often a
_forest_ of signs, which some readers _will_ not, and others _can_ not
penetrate; so that, for many, Theory might as well not exist. This evil
is increased when, as it sometimes happens, these suppositions are laid
so far from reality, as to leave the result, though correctly deduced,
further from the truth than the point to which a sound understanding
unassisted by science, would have carried it. To this extreme
discrepance of views between theoretical and practical men, may be
ascribed their well-known antipathy to each other--in indulging which,
they are alike to blame! since no theory inconsistent with fact can be
complete; nor any fact be adduced, that a perfect theory will not
account for and confirm.
Happily these discussions do not affect my present purpose. For although
I shall offer nothing contrary to sound theory, I do not consider that
as my subject; but make it my business to present rational methods of
producing useful effects.--In other words to describe these Inventions
as connected with immediate Practice. And if, hereafter, it should
become desirable to resume the discussion of any _principle_ relating to
these subjects, I shall cheerfully enter upon it; but hasten, mean
while, to do what seems more important--to place the subjects themselves
beyond the danger of being wholly lost, whatever may befall me in the
course of those events which are still among the secrets of Heaven.
In the pursuit of knowledge, in general, it is often desirable to trace
it from its _upper_ source; and to know all the circumstances that have
attended its progress, down to the very moment when it falls under our
observation. Nor is it a matter of indifference to examine the minutest
form which talent assumed, in the young mind whose subsequent efforts
have engaged our attention, or gratified us with more varied and solid
productions. In this view I have presumed to think myself justified in
commencing this Work, by a succinct reference to those feeble efforts
which marked my first steps in this career. Young I then was, and my
musings puerile indeed! But they were original: they were the links of a
chain which time has not yet snapt asunder--and of which my honoured
Father saw the connection with my subsequent labours, long before I
thought, myself, of any thing but working for the purposes of amusement;
or, in the childish phraseology, of “playing at work.”
[Illustration]
Should any reader then enquire what were my first avocations? the answer
would be, I was (in imagination) a Millwright, whose Water-wheels were
composed of Matches. Or a Woodman, converting my chairs into _Faggots_,
and presenting them exultingly to my Parents: (who doubtless caressed
the workman more cordially than they approved the work.) Or I was a
Stone-digger, presuming to direct my friend the Quarry-man, _where_ to
bore his Rocks for blasting. Or a Coach-maker, building Phætons with
_vaneer_ stripped from the furniture, and hanging them on springs of
Whalebone, borrowed from the hoops of my Grandmother. At another time, I
was a Ship Builder, constructing Boats, the sails of which were set to
a side-wind by the vane at the mast head; so as to impel the vessel in a
given direction, _across a given Puddle_, without a steersman. (See
Plate 2. Fig. 3.) In fine, I was a Joiner, making, with one tool, a
plane of most diminutive size, the [relative] perfection of which
obtained me from my Father’s Carpenter a profusion of tools, and dubbed
me an artist, wherever his influence extended. By means like these I
became a tolerable workman in all the mechanical branches, long before
the age at which boys are apprenticed to any: not knowing till
afterwards, that my good and provident Parent had engaged all his
tradesmen to let me work at their respective trades, whenever the more
regular engagements of school permitted.
Before I open the list of my intended descriptions, I would crave
permission to exhibit _two_ more of the productions of my earliest
thought--namely, an Instrument for taking Rats, and a Mouse Trap:
subjects with which, fifty years ago, I was vastly taken; but for the
appearance of which, here, I would apologize in form, did I not hope the
considerations above adduced would justify this short digression. If
more apology were needful.... Emerson himself describes a Rat-trap: and
moreover, defies criticism, in a strain I should be _sorry_ to imitate!
my chief desire being to instruct at all events, and to please if I can:
without, however, daring to attempt the elegant PROBLEM, stated and
resolved in the same words--“Omne tulit punctum, qui miscuit utile
dulci.”
[Illustration]
The town of Cirencester (my native place) is intersected by several
branches of the river Churn, whose waters are pure and transparent, and
whose banks, formerly, were much perforated by the industry of the Rats
that had made them their residence. These holes had generally two
openings; one at or near the surface of the ground, and the other near
the bottom of the river: so that the rats could range the fields from
the former, and dive into the water from the latter--where they were
often seen gliding along the bottom, either up or down the stream. The
Instrument for taking them in these circumstances, was no other than my
Father’s Walking-stick, (represented at A. Fig. 1. Plate 2.) connected
with the curve B by the joint C; the curve having a string fastened to
it, which, passing through the body of the stick, rose to the hand at D,
for the purpose of closing the fork at the proper moment. The Machine,
thus constructed, was put over the rat’s back while in the act of
diving; and by pulling the string C D, he was sufficiently pinched to be
drawn out of the water, where a Dog stood ready to dispatch him.
On the Mouse-trap (Fig. 2. and 4.) more thought was bestowed. It
appeared adviseable (I remember) to lay the deceptive plan rather deep:
and to lull the little animal into a false security till the snare had
taken full effect; and even then to hide from her some of its horrors
till she was far enough from this vestibule of misery, _not_ to deposit
there any of those tokens of distress that might deter other mice from
following her example. The trap then, consisted of a _long_ passage,
formed spirally round the surface of a Cone, like the figures we have of
the Tower of Babel. This passage is uncovered in Fig. 4 to shew the
entrance E, and the subsequent gates F G H, &c. which like the valves of
a pump, gave easy entrance to the victim, but forbade her return. At the
length of a mouse from the outer gate E, was placed the first bait N,
say a small rind of cheese, well toasted to allure, but nailed down to
prevent its removal. Its position was further indicated by a train of
meal reaching from it to the outer gate E; which latter was nicely hung
on pivots inclined a little to the perpendicular, so as to open with
ease but never fail to close itself again. It had besides an horizontal
plate O, fixed to its bottom on the inside, so that if the mouse
attempted to open it that way, she trode on this plate and destroyed the
result of her own efforts.
When, therefore, the little wretch had passed this barrier, she was in
reality taken: but unconscious yet of danger, she nibbled the first bait
with pleasure, and then skipped forward in search of more substantial
food: but to obtain this she must pass more of these faithless gates, F
G H, &c. which with progressive effort she opened, and at length found
the inner compartments replete with good things, on which she fed to
satiety, and then only began to think of her situation. Nor yet, with
_much_ alarm: for at the end of this labyrinth, so easy of access, she
hoped to find an easy exit. But alas, these hopes were illusive.
Instead of light, she found the _dark_ gallery O; the least evil of
which was to be too narrow for two mice abreast, since it overhung a
tremendous cavern, Q, that entirely occupied the Cone below, and was
filled with water deep enough to drown her, were she to fall, or be
jostled into it. And one of these disasters she could hardly escape! for
other mice would not fail to be beguiled into this cruel Bastille; to
reach the same spot; and finally, to plunge her into this watery grave.
Having endeavoured to recollect the substance of these youthful attempts
to unite cause and effect, or to fulfil a given purpose by preconcerted
means, I now turn to things of greater importance, and more worthy to be
the theme of my readers’ attention. The subjects to be presented will
observe a miscellaneous order; since they have not only originated at
different periods, but offer likewise different degrees of interest--to
_equalize_ which throughout the Work, appears a desirable attempt. As to
the _manner_ of treating each subject, it will be, generally, to
describe the Machines by a reference to the Figures; and then to add
some remarks on their date, construction, properties, and uses.
PART FIRST.
A NEW CENTURY OF
Inventions.
A
DYNAMOMETER;
OR,
_Machine for measuring Power and resistance while in Motion_.
Dynamics being a science that relates to bodies in motion--comprehending
not their weight only, or their velocities only, but the product of the
one by the other; so the Dynamometer is a mean of measuring both these
circumstances together, and thus of making known the _momentum_ of a
power or resistance in motion. As this Machine has a connection more or
less intimate with almost every other, it seems entitled to the first
place in this collection. Its description follows:
In Plate 3, Fig. 1 and 3, M M, represent two cheeks, standing parallel
to each other, and forming a cage or frame by means of the cross bars E
and the nuts F G. A P, Fig. 2, is the principal axis of the Dynamometer,
fixed to the wheel R N of which it is the centre of motion. It has a
square end A, formed to receive the wheels and other supplemental parts,
to be mentioned below. After the square A, comes a bearing E, to fit the
steps in the frame; and beyond the wheel R N is a cylindrical part O,
fitted to the hollow axis T of the wheel or frame I K, (Fig. 4); and in
fine the form P of this shaft fits and turns in the _cannon_ of the
axis B H, of the wheel C D; so as, when put together and connected with
the frame I K, to assume the form C R F G of the third figure. L P, Fig.
3 and 4, are two intermediate wheels (thus placed to balance each other
on the common centre T) whose axes turn on proper steps in the frame I
K; and which by their teeth connect the motion of this frame with that
of _both_ the wheels R N, and C D.
Such are the parts of the Dynamometer properly so called; and they are
shewn as in their places in Plate 1, where the parts above described, as
far as visible, are marked with the same letters. Moreover, this figure
shews a scale-bason P, to receive the weights used to measure equable
powers, as will be seen hereafter.
Plate 4 contains some of the auxiliary parts of this Machine. But before
we proceed to describe them, it may be proper to observe that the
_measuring power_, by the action of which at K, (Plate 1) the energy of
the _force_ is transmitted to the _resistance_, must, to meet every
case, be susceptible of change, according as the resistance or force to
be measured is uniform or convulsive. For example, in a mill grinding
corn, driven by a fall of water, the whole process is sensibly uniform,
and a weight at P is the proper measurer. But if it were desired to
measure the effect of a pump driven by water, or of a tilt hammer worked
by a Steam Engine, then the measuring power at P must be a spring: for
in these cases the _vis inertiæ_ of a weight would add to its force of
gravity when suddenly raised, or detract from it when the resistance
should suddenly give way. Whenever therefore, the force and resistance
are both _equable_, a weight will best measure them; and when _either_
is convulsive, a spring: but a spring so equalized as to offer the same
resistance at every degree of tension it may have to sustain.
In the 6th. and 7th. Figures, (Plate 4) these demands are fulfilled. The
first represents a barrel-spring, similar to that of a watch, but
_surrounded_ by a fusee, the increasing radii of which compensate for
the increased tension of the spring in the barrel G; so that the action
of the system on the chain is always the same.
The 7th. Figure exhibits a spring adapted to heavier purposes. It is a
cylinder nicely bored and hermetically closed at bottom; in which works
a Piston P plunged in oil, which when forcibly drawn up forms a vacuum
in the cylinder, into which the atmosphere endeavouring to enter, acts
like a spring on the Piston; and preserves the same stress whatever be
the height of this Piston in the cylinder.
This then, is also an _equalized Spring_, such as these experiments
require; but it is _not_ my invention. I first saw a vacuum used, as a
spring, by my noble Patron, the late Earl Stanhope: to whose mechanical
attainments, I owe this tribute of applause on the present occasion.
In the three Figures of this Plate, 8, 9, 10, are shewn two of the means
I use for creating those factitious resistances that are sometimes
wanted in the process of measuring power. In Fig. 8, E H F, is a gripe
or brake, such as millers use to stop their wind-mills with; fixed under
L, it surrounds the wheel E H, and is then fastened to the end F of the
lever K L. The brake is thus pressed with greater or less force against
the wheel, as the weight I is placed more or less distant from the
fulcrum L of the lever. By these means a resistance of the equable kind
is produced, capable of being adapted to _any_ power it may be wished to
measure; which makes this Dynamometer a real _tribometer_ or measurer of
friction.
The second kind of resistance brought forward in this Plate, is a
Pendulum P (Fig. 9 and 10,) set a vibrating by a pallet-wheel A B,
connected with the axis of resistance; and working in the pallets N. It
appears besides, in the Figure, that the times of vibration can be
changed by the mechanism T N R, which raises or lowers the ball P. This
then, is another resistance, such as we sometimes want: but it is also a
mean of finding the quantity of resistance that a vibrating body opposes
to motion, when oscillating in times _not_ those due to its length as a
pendulum. In other words it is a mean of measuring _vis inertiæ_
itself--which an _astounding_ modern writer declares does not exist!
I hasten to give a description of certain other parts relating to the
measuring system: and some methods of connecting with the Dynamometer
the several kinds of forces it may be desirable to examine.
In Plate 5, Fig. 12, A X represents a Crank or Handle with a variable
radius, the intent of which is to adapt a man’s strength to the velocity
and intensity of any resistance he may have to overcome. The manner is
this: B is a Screw pressing on the quadrant, and fixing the arm C X to
any required angle with the part A C: thus determining the virtual
radius of the handle.
Fig. 14, shews a method of applying to the Machine the force of a man
pumping: for the catch N permits the handle O to rise alone, but carries
round the wheel R, at every downward stroke, while the fixed catch C
secures all the forward motion thus given. The same Figure shews, at B,
the force of a man in the act of _rowing_: for the catch M permits the
lever V M to recede when the man _fetches_ his stroke, and carries the
wheel round when he _takes_ it. An operation, by the bye, which I think
the best mode of employing human strength, if every possible advantage
is taken of the method.
The 13th. Figure shews the last method I shall now offer of adapting
power to the Dynamometer. T S represents the Piston of a Steam Engine,
the rod of which is formed of _two_ bars, including between them the
chains F G and F D, the first of which is single, merely to carry back
the acting wheel; and the last double, to draw round the ratchet wheel
E, by the catch O, at every stroke of the Piston.
I must obviate here an objection that may strike some readers. This
Piston T S, acts only one way, like that of an atmospheric engine, a
thing now quite out of date! I answer that this figure is chiefly
intended to give the _idea_; and shew a rotatory Steam Engine that
_might_ act without a fly. I will add, that it is my intention some day
to bring forward a method of using these suspended actions, better than
by a mere ratchet wheel: and especially without incurring danger from
the length of the ratchet teeth, or the blow they suffer at the
beginning of the strokes. But of this more hereafter.
A short description will suffice for the mechanism of the 18th. figure
(Plate 6), which is intended to convert the alternate pressure of a
man’s feet into rotatory motion, and then to measure his _power_. To do
this two catches A B, take into the teeth of the same wheel M, and each
catch carries an arm, P, embracing somewhat stiffly the boss of the
wheel. The treadles have a common centre at E, and are fastened to the
same rope going over a pulley, F, so as for the depression of the one to
raise the other. Again, the pulling bars C D, are connected with the
treadles, and from the form of the catches, it is evident (since the
levers move with some stiffness), that the first effect of an ascending
motion will be to draw the rising catch out of the teeth, and keep it
out until arrived at its greatest height; when the very beginning of
its descending motion will bring the catch into the teeth again, and
thus carry round the wheel at every downward movement of the treadle;--a
method this of making a ratchet work without rattling upon the wheel.
The mechanism shewn in figure 19, is intended to produce another of our
factitious resistances; and it serves likewise to make experiments on
the resistance of the air. It is a fly, meeting with an _equable_
resistance as does the fly in the striking train of a clock. The wheel
W, is put on the axis of resistance of the Dynamometer; and its teeth
geer in those of the vertical shaft L H. This latter is perforated from
above, and has an open mortice all along its body, which a small bar
penetrates, meeting at bottom the ring H, to which it is fastened by a
pin going through the mortice. Again, this ring H, is moved, downward,
by the rollers of the sliding bracket P, which has its motion from the
wheel and rack G: and finally, the leaves I K slide in the horizontal
frame; and when the machine turns _would_ obey the centrifugal force and
fly outward; but are withheld by the cords N O, which passing over the
pulleys N O, and under those L M, are then fixed to the frame above L.
When, now, this Machine is used, and the fly made to revolve swiftly,
the leaves I K, oppose a certain resistance to the rotatory motion; and
if _this_ be too feeble, the key G must be turned backward, which will
permit the ring H to rise, and the wings I K to recede from the centre.
But if this resistance is already too strong, the key G must be turned
forward, and the wings brought nearer: between which extremes, a point
will easily be found where the resistance of the air will _expend_ just
power enough to balance that brought into the Dynamometer through the
_power-axis_; and thus to keep the measuring weight in the position
required for any given experiment.
There remains only one part to be described as belonging to this
Machine. It is represented in Plate 5, fig. 15, and is a graduated bar,
made to fit in the holes K, of the measuring cylinder I K Plate 1: and
to carry one of the arcs A A, which thus serves to extend, virtually,
the radius of that cylinder to any required dimension.
It is now time to shew something of the manner of using this Dynamometer
in the measurement of forces. Let the object then be to measure the
power expended by a Horse in drawing a Carriage.
To do this, we fix a Drum (see fig. 16,) of equal radius with the
measuring cylinder, on the power axis A; and a similar Drum to the
resisting axis H. After firmly fixing the Machine, we place the Carriage
at a distance behind it in the plane of the Drum H; and carry a rope
from that Drum to the Carriage: on the other hand, we fill the first
Drum A, with a coil of rope, to which the Horse is harnessed; and while
he travels in the plane of the Drum A, the scale P (Plate 1,) is loaded
with weights, until the Carriage follows the horse’s motion without any
(or with little) agitation to the scale P: at which moment the _power_
employed _is equal to one half the weight at P, multiplied by the space
gone through both by the Horse and the Carriage_.
If it were now desired to find the power of a man turning a crank or
handle, we should take that given in the figure 12, and fix it to the
power-axis A. We should also take the fly-system shewn in fig. 19, and
place it on the axis-of-resistance H. Then causing the man to turn the
Machine, we should put _twice_ as much weight into the scale P, as his
strength was thought able to bear. Then if he thought the work too
heavy, we should draw inward the leaves of the fly, and take away part
of the weight P, until the man were satisfied he could work with
convenience: and when, as before, the weight P should overcome the
resistance of the fly I K, without either rising or falling, (sensibly)
then the _power_ expended would be _one half of the weight P, multiplied
by the space described by the man’s hand in the act of turning the
handle_.
It may occur to some of my readers that in these experiments the whole
effect is not actually _measured_: since the space described by the
horse or the man’s hand, must be determined after the experiment. I
answer that these quantities, necessarily _variable_, must bear an
inverse proportion to the weight P: and in all cases, this weight
multiplied by that space, must give the _power_ or momentum required.
Besides, it is most easy to add a piece of mechanism that shall count
the number of turns, and express them _in space_, by the inspection of a
graduated scale. Nor need we stop here. The duration, in time, of any
experiment, may also be recorded by the Machine itself. These are things
so naturally connected with the subject, that I cannot feel it
necessary, with so much before me, to attempt exhausting them. But
_this_ I engage to do: if any serious difficulty should actually stop
any reader in this career of investigation, I will obviate such
difficulty at some convenient future period. And mean while those
persons who have aptitude for such subjects, will find in this Machine,
ample scope for extending their enquiries; and comparing many mechanical
realities with the deductions of Theory, thus amending and conciliating
the conclusions both of Theory and Practice.
I have said above, that the weight or spring acting on the measuring
cylinder at K, _must_ be equalized: but in reference to _some_
applications of this Machine to real use, I would modify that precept a
little. I should, indeed, always like the principal action to be of a
constant nature: with a supplementary part of less intensity, prepared
to add something to the former; and this, for the purpose of meeting
spontaneously the case of any unexpected addition of the moving power.
Thus in Plate 1, if P be a weight _nearly_ adapted to a given
resistance, I would (to prevent accident, from its being overraised by
any sudden jerk of the power,) hang one or more heavy chains under the
scale, which drawn from the ground to a certain length, would add a
known quantity to the measuring power; and transmit with a certain
softness to the work, the unequal action of the _mover_.
One word on the _friction_ of this Machine. All friction must of course
be avoided as much as possible; but as it will be nearly the same in
every class of experiments, it is not of great importance. The same may
be said of the _vis inertiæ_ of the parts, _in convulsive motions_. The
parts would, of course, be made as light as a proper strength would
permit. My mechanical readers will easily supply these small items of
foresight; to anticipate the whole of which would make this Work
interminable.
OF A NEW KIND OF
BARREL SPRING,
_To lengthen the going of Clocks, Jacks, &c._
Although this invention does not properly constitute a _new Spring_, yet
it produces effects both new and important. It protracts almost
indefinitely the action of a barrel Spring, and thus reduces
considerably the number of wheels in a clock or other spring-driven
machine. This effect is produced by _setting the two ends of the spring
at variance_; or making them _act one against another_: for as these
opposite tendencies can be made nearly equal, one end of the spring will
be wound up _almost_ as much as the other end runs down: thus prolonging
the effect in any desired proportion. It will be making known the
principle, to describe the _first motion_ of a clock founded upon it.
In Plate 7, fig. 1, A is the spring barrel, to which is fixed a _wheel_,
B, of 96 teeth, working in C, a pinion of 17. E is another _wheel_ of 92
teeth, working in F, a pinion of 22: both pinions being _fixed_ on the
same arbor, I G. The smaller wheel E, turns on a round part of the axis
H D; and is connected with its motion in the backward direction only, by
a ratchet wheel R, fixed on a square part of the same arbor. _As usual_,
this latter has a cylindrical boss within the barrel A, to which the
_inner_ end of the spring is hooked; as its outer end is, to the rim of
the barrel; and thus does the wheel B (when the clock is wound up) tend
to turn _forward_ as shewn by the arrow B; while the wheel E, tends to
turn _backward_ in the direction of E, the second arrow. But these
opposite tendencies are _not_ equal; because the wheel B is larger, and
acts _disadvantageously_ on C, the smallest pinion; while the wheel E is
smaller, and acts to _advantage_ on the larger pinion F: so that there
is a decided tendency in the whole to turn _backward_. Now, to find
precisely what is the effect of that tendency, we observe that when the
barrel and the larger wheel B, have made _one_ revolution round the
common axis H D, the pinions C and F will both have made 96/17 of a
revolution (being the quotient of the division of the wheel B by the
pinion C:) and since the larger pinion of 22 teeth, works in the smaller
wheel of 92 teeth; this latter wheel in the same time will have made
96/17 of 22/92 of a revolution, or 1,350 of a turn very nearly. The
difference then between this quantity and unity, namely the decimal
0,350, is what the spring has really _gone down_ during one turn of the
barrel. And as the whole number of coils in the spring are 10, the
number of turns of the barrel to uncoil it entirely, will be 10/0,350 or
10000/350 equal to 28,57 nearly: instead of _ten revolutions_ which it
would have been on the common principle.
It is almost superfluous to add that this prolongation of the time might
have been greater, had I not been confined to the above numbers, for
want of others _more nearly alike_, and having a common difference, on
my engine.
An important remark here presents itself, viz. that the best properties
of this invention are unattainable by the use of the common
_geering_--the friction of whose teeth would have absorbed the small
rotatory tendency thus retained; and in which system, also the working
diameters of the wheels could not have been defined with sufficient
exactitude. This then, is one of the cases in which (as I have observed
in a former work) my late Patent System of Geering has “given rise to
machines that could not have existed without it,”--which it does by
possessing exclusively the property of realizing (sensibly) the whole
calculated effect; and working without commotion or assignable friction.
It may please some of my readers to be informed that this System, and
the means of executing it in every dimension, will hold a prominent
place in some future page of this essay.
Referring again to the figure 1, the teeth X X, Y Y, are there placed to
give a first idea of this principle: and they are unaccompanied by
others, to avoid the confusion of lines that would have arisen from
attempting to shew all the teeth, in their due position, on so small a
scale. These things will claim all our attention when the System itself
comes under examination.
The above representation of this Machine may leave a technical
difficulty on the minds of clock makers relative to the _winding up_ of
this spring; which, in the present state of things, will suspend, for
the time, it’s action on the pendulum: for in order to effect it, (in a
reasonable number of turns) the introduction of the key _must_, by a
proper check-piece, be made to stop the wheel B, and leave it again at
liberty when the key is taken out: in which case ten turns of the key
will effect the winding, although the Machine should be calculated to
_give out_ forty turns in the uncoiling of the spring. But if the wheels
B and E had changed places; that is, if E had been fixed to the barrel
A, and B been connected with the ratchet wheel R, then the act of
winding up would have taken place in the opposite direction; or in that
which tends to _keep up_ the motion of the pendulum, in which case,
however, the machinery of the clock must have borne the _whole_ stress
of the spring during the act of winding, instead of the small portion it
sustains when the two ends counteract each other.
But I anticipate another objection to this method of employing a barrel
spring: which is the inequality of stress, when the spring is much or
little wound. The answer is, that many clocks and watches are made to go
well without fusees; either by modifying the thickness of the springs,
or employing only a few of the middle coils. My Invention may, perhaps,
help to nurse this System to perfection: if not, its influence will be
the more confined, but in no wise destroyed.
OF
A PARALLEL MOTION,
_Being a combination of the Crank with the Epicycloid_.
A B, Plate 7, fig. 2 and 3, is a ring or wheel fixed to the frame C D;
and having all round it’s inside, teeth directed to the centre. F is a
wheel of half the diameter, and exactly half the number of teeth of the
wheel A B. It turns on a Crank-arm, E F, whose radius is equal to one
quarter of the diameter of the fixed wheel A B--in the centre of which
the axis of this Crank finds it’s due position. The latter, therefore,
so conveys the wheel F round the inside of the fixed wheel A B, that the
teeth of both are constantly _geering_ to a proper depth: and a stud
being fixed on the face of the wheel F, opposite the middle of any
tooth, a, directly over the centre of the Crank E, this stud describes
the perpendicular diameter of the large wheel: and will either receive
motion from the rod R of a Steam Engine Piston, so as to give the fly I
K, a rotatory motion; or communicate to a Pump-piston a reciprocating
motion, drawn from the rotatory one of the fly, when _that_ is the
effect desired to be produced.
This Invention will be remembered, as having procured me a remunerating
Medal from the late Napoleon Bonaparte, then first Consul of the French
Republic. That period, however, (1801) was not the real date of this
production, although then first made _public_. I have proof, on the
contrary, of its existence with me several years before; and it is
generally ascribed to me by the publicists. I might quote in particular
Doctor Gregory: who likewise mentions its having been executed by
Messrs. Murray and Wood, of Leeds, subsequently to it’s exhibition at
Paris. The Doctor commits, however, a small error in calling me an
Anglo-American; but this is accounted for by my then living in a country
where to be an Englishman was itself a crime! and where some kind
friends, wishing to hide me from the relentless decrees of the day, felt
justified in using this sort of pious fraud in my favour: a resource
from which, though I did _not_ authorize it, I reaped no small
advantage; and still think of with gratitude, though not with unmixed
approbation.
I think it a duty more imperious than agreeable, to expostulate a little
with Messrs. Lanz & Betancourt, on their apparent partiality in giving
an account of this Machine. In their work on the construction of
machines, art. 97, page 37, they make M. de la Hire the inventor of it,
by the terms in which they introduce his treatise on Epicycloids: and
they leave me the thread-bare merit of having “_presented a model_ of
this movement at the last exposition but one,” &c. Now, although I do
not attach great importance to this kind of misrepresentation, I cannot
but observe, that neither my Machine or their description of it can be
called a Theorem! nor especially a theorem relating solely to the
Epicycloid, as M. de la Hire’s was. These Gentlemen knew that he
insisted principally on the application of this curve to the teeth of
wheels, _with which my Invention has nothing to do_. On the contrary, my
Machine is a combination of two curves at least, on which de la Hire
says absolutely _nothing_. Is this then inadvertency? or is it uncandid
nationality? I hope, the former.
A further remark on the utility of this System as a first motion, may be
of use in this place. It respects the _geering_ of the fixed and
moveable wheels A B, and F, on the _perfection_ of which depends the
truth of the statement, that the stud, a, describes a diameter of the
large wheel. Now, perfection is too much to be expected from common
teeth when of the necessary strength; so that my Patent Geering is an
indispensable complement to this Invention: as by its use, the principle
is made practically true; this line becoming really straight, and this
motion, under proper circumstances, being unattended with noise or
commotion. In a word, I cannot move a step in this mechanical field,
without meeting with instances where the new System shews its
superiority to the old: whence it becomes a duty for me to commence the
consideration of this subject in the very next _part_ of this
publication.
OF
A SYSTEM OF CONCENTRIC PULLEYS,
_Already known as White’s Patent Pulleys_.
These Pulleys have been frequently described since I first entered my
_specification at the Patent Office_. The Authors of the Encyclopedia
Britannica; the Rev. Mr. Joyce, in his juvenile philosophy; and Dr.
Gregory in his mechanics, have all adverted to them. In the latter work,
I find the following quotation from my own description, thus introduced:
A very considerable improvement in the construction of pulleys has been
made by Mr. James White, who obtained a Patent for his Invention, of
which _he_ gives the following description: “Fig. 4, Plate 7, _of this
work_, shews the Machine, consisting of two pullies, Q and R; the former
fixed, the other moveable. Each of these has six concentric grooves,
capable of having a line put round them, and thus of acting like as many
different pulleys having diameters equal to those of the grooves.
Supposing then, each groove to be a distinct pulley, and that all these
diameters were equal, it is evident, that if the weight 144 were to be
raised by pulling at S, till the pulleys touched each other, the first
pulley must receive the length of line as many times as there are parts
of the line hanging between it and the lower pulley. In the present
case there are 12 lines, b, d, f, &c. hanging between the two pulleys,
formed by its revolution about the six upper and six lower grooves.
Hence as much line must pass over the uppermost pulley as is equal to 12
times the distance of the two. But, from an inspection of the figure, it
is plain that the second pulley R S, cannot receive the full quantity of
line by as much as is equal to the distance betwixt it and the first. In
like manner, the third pulley receives less than the first, by as much
as is equal to the distance between the first and the third; and so on
to the last which receives only 1/12 of the whole: for this receives
it’s share of line n, from a _fixed_ point in the upper frame which
gives it nothing: while all the others in the same frame receive the
line partly by moving to meet it, and partly by the line coming to meet
them.”
“Supposing now these pulleys to be equal in size, and to move freely as
the line determines them, it appears from the nature of the system, that
the number of their revolutions, and consequently their velocities, must
be in proportion to the number of suspending parts, that are between the
fixed point above-mentioned, (n) and each pulley respectively. Thus the
outermost pulley would go twelve times round in the time that the pulley
under which the part n of the line passes, (if equal to it) would
revolve only once; and the intermediate times and velocities would be a
series of arithmetical proportionals of which, if the first term were
l, the last would always be equal to the whole number of terms. Since
then, the revolutions of equal and distinct pulleys are measured by
their velocities, and that it is possible to find _any_ proportion of
velocity on a single body running on a centre, viz. by finding
proportional distances from that centre; it follows, that if the
diameters of certain grooves in the same body be exactly adapted to the
above series, (the line itself being supposed inelastic and of no
magnitude) the necessity of using several pulleys in each frame will be
obviated, and with that some of the inconveniences to which the use of
the common pulley is liable.”
“In the figure referred to the coils of rope, by which the weight is
supported, are represented by the lines a, b, c, &c. a is the line of
traction commonly called the fall, which passes over and under the
proper grooves, until it is fastened to the upper frame just above n. In
practice, however, the grooves are not arithmetical proportionals; nor
can they be so, for the diameter of the rope employed must be deducted
from each term, without which, the small grooves to which the said
diameter bears a greater proportion than to the larger ones, will tend
to rise and fall faster than the latter, and thus introduce worse
defects than those which they were intended to obviate.”
“The principal advantage of this kind of pulley is, that it destroys
lateral friction, and that kind of shaking motion which are so
inconvenient in the common pulley; and lest, says Mr. White, (I quote
Dr. Gregory) this circumstance (of a long pin) should give the idea of
weakness, I would observe, that to have pins for pulleys to run upon, is
not the only, nor perhaps the best method: but that I sometimes use
centres fixed in the pulleys, and revolving on a short bearing in the
side of the frame, by which strength is increased, and friction much
diminished: for to the last moment of duration, the motion of the pulley
is circular, and this very circumstance is the cause of it’s not wearing
out in the centre as soon as it would, assisted by the ever increasing
irregularities of a gullied bearing.--These pullies when well executed,
apply to Jacks and other Machines of that nature with great advantage:
both as to the time of their going and their own durability: and it is
possible to produce a System of pulleys of this kind, composed of six or
eight parts only, and adapted to the pocket, which by means of a skain
of sewing silk, would raise more than a hundred weight.”
There are several real and solid advantages attending the use of this
pulley; some of which are only hinted at in this description. I have
thought, therefore, it might be useful to introduce here an account of
some trials which the System underwent a few years ago at
Portsmouth,--at the request of an Officer of the Navy, who had
_re-invented_ it with some ingenious additions to my ideas. Not being at
present in correspondence with that Gentleman, I hardly think myself at
liberty to mention his name; but fully so to give an extract from the
report which followed these experiments--in which the superiority of
the System _in respect of power_, is made evident, although some less
favourable circumstances prevented its adoption on that occasion.
“With a view to comparison, it was settled with Lieutenant S. that his
blocks should be made to correspond with the treble and double 16 inch
blocks of a 24 gun ship, which carry a 4-1/2 inch rope. The sheeves in
the new blocks are fixed upon the pin, revolving therewith, and are of
different diameters proportioned to the velocity of the parts of the
rope that pass over them; they are also reeved with a double rope so
that there are two grooves of each size, the diameter of the smallest
groove in this tackle being 2-8/12, and of the largest 15 inches. The
diameter of the sheeves of the common blocks would have been (as usually
made) 9-1/8 to the bottom of the grooves, but were reduced at the
request of Lieutenant S. in the treble block to 8-1/8, and in the double
block to 8-7/8, in order that the sum of the diameters of the sheeves in
each tackle should be the same. The Lieutenant intending in the first
instance, to have used a roller under the pin, for the purpose of
diminishing friction, but afterwards laying aside this idea on account
of it’s complication, was the reason that he had not made his sheeves in
the same proportion with the common blocks: the weight and length of the
respective blocks are as follows:
Weight. Length.
Lieutenant S.’s treble blocks 131lbs. 24 Inches.
Common ditto 78 „ 16 „
Lieutenant S.’s double block 73 „ 21 „
Common ditto 60 „ 16 „
Lieutenant S.’s single block 22 „ 17 „
Common ditto 34 „ 16 „
“Lieutenant S.’s blocks were reeved with a 2-1/2 inch double rope, and
the common block with a 4-1/2 inch single rope, and both tackles
suspended from a beam, and their respective falls let over the single
blocks, so as to keep the weight applied as a power, just clear of the
weight to be lifted, thus forming a power of six to one; the following
experiments were made:
Weight very Power required Power required
slowly lifted. with Lieutenant S.’s blocks. with the common blocks.
℔s. ℔s. ℔s.
336 88 124
672 169 252
1344 312 448
2688 588 808
5376 1101 1344.
“After reeving the common blocks with a 3-1/2 inch rope in lieu of a
4-1/2 inch rope, it was as follows: 5376 1101 1232.
“It must be observed, that the double 2-1/2 inch rope in Lieutenant
S.’s blocks, is not of equal strength with the single 4-1/2 inch rope
first used in the common blocks; and that his blocks had an undue
advantage in the first experiment over the common blocks, in respect to
the pliability of the rope. The rope should therefore, be taken larger
in the one or smaller in the other case, on this account: The common
blocks were reeved in the last experiment, with a 3-1/2 inch rope, which
is as near as may be of the same strength as the double 2-1/2 inch rope.
“In these experiments it was observable, that the tar was much more
squeezed out of the parts of the rope that passed over the smallest
sheeves in Lieutenant S.’s blocks, than out of those passing over the
larger sheeves, or out of those passing over the sheeves of the common
blocks; by which, as well as by the nature of the thing, we judge that
with blocks requiring such small sheeves, the ropes would be more
crippled and broken than by the common blocks, especially if any
constant strain or weight in motion, as on ship board, should be held by
them. In regard to our opinion of the merits of the blocks proposed by
Lieutenant S. compared with common blocks, we beg leave to submit, that
the mechanical principle of them is very inviting, and it is not to be
wondered that an ingenious person should pursue the idea; yet _allowing
there would be a saving of power_, which is attained in so great a
degree with the common blocks, but considering the greater complication,
weight, and expence of these blocks, and their greater disposition to
cripple the ropes, we do not perceive any application of them on ship
board, for which we could recommend them in preference to common blocks;
neither do we perceive any purposes on shore, for the services of the
dock yards in which to recommend their application in preference to the
other powers in use.”
To this account of the result of these experiments, I beg leave to add
what seems to be a great improvement of this System: namely, a method by
which the diameters of the larger pulleys are considerably lessened; and
thus the principal, if not the only objection, obviated. It has been
before observed, that the larger pulleys, as Q R, are the ultimate terms
of an arithmetical progression, beginning at unity; and that
consequently they cannot be very small, even though the first terms
should be so. If a first pulley were only one inch in diameter, the
_twelfth_ pulley would be twelve inches,--where we see a large and
inconvenient difference. But this evil I now obviate, by placing at the
beginning of the series, one or more _loose pulleys_, over which to
_reeve_ the cord, before the concentric or fixed grooves begin; thus
lowering the _ratio_ of the progression, and keeping the larger pulleys
within bounds. For example, the smallest fixed pulley (supposed as
before, to be one inch in diameter) I now make the _second_ of the
series instead of the first: and therefore, the second _fixed pulley_ is
to the first as 3 to 2, instead of being as 2 to 1; for the same reason,
the third fixed pulley is to the second as 4 to 3; and in a system of
12 pulleys, (with one loose one) the respective terms will be as
follows:
Terms 1----2----3----4----5----6----7----8----9---10---11---12
loose;2/2; 3/2; 4/2; 5/2; 6/2; 7/2; 8/2; 9/2;10/2;11/2;12/2