theory; which is precisely the length it is drawn to compared with
_that_ _e f g_, namely twice as long. Thus the four triangles, drawn to
the right and left in this diagram, represent the plates for the wheels
of the following diameters respectively:
No. 1, a wheel _equal to the plate rim_ _c d_;
2 do. do. to 1/2 do.
3 do. do. to 1/3 do.
4 do. do. to 1/4 do.
A small anomaly, _of form_, may be mentioned here to prevent mistakes.
The shaded triangle _e f g_ in the Plate, _looks_ higher than the rest:
but if higher, it is also _longer_ in the same proportion; and the
roller _p_ never reaches the bottom: so that the _effect_ of this Plate
is the same as though it resembled the others in every respect. In
general the effect of the Plates depends on their length _compared with
their height_: and indeed they must be made _higher_ than the thickness
of the wheel to be cut, that the latter may disengage itself from the
(fixed) cutter both above and below.
It is proper to observe, that for every _pair_ of wheels there must be a
_pair_ of plates; one leaning to the right and the other to the left,
(see the diagram) but, as before said, the degree of obliquity _must_ be
different in each pair, except in the case of equal wheels, when the
_same_ plate serves for both; only turning it to the right for one
wheel, and to the left for the other. Nor does this offer any
difficulty, as the plates are made of _common tin plate_: which is
easily brought to fit the rim, whichever way it is applied. I shall now
add another example of the process for finding the length of the plates:
and to that end repeat that the _plate rim_ _c d_, is 22 inches in
diameter, or 11 inches radius. Supposing then that we wished to cut a
pair of wheels, _one_ of them being 1 inch in diameter and the other 12
inches; _both_ to have teeth inclined 15 degrees to the axes; (as
without _that_ they could not work together) to do this we must _effect_
these two proportions:
(1) 1/2 inch (radius of small wheel) is to 11 inches, (radius of
plate rim) as 268 parts (of which the height of the plate is 1000)
to another number, which is the length of the plate sought: measured
on a scale of parts of the same magnitude.
(2) 6 inches, radius of the large wheel; is to 11 inches radius of
plate rim; as 268 parts (as before) is to another number, which is
the length sought for this second plate.
Both proportions being effected, the first plate is 5896 parts.
And the second 491.33 do.
The one of course, to be directed toward the right hand, and the other
toward the left, on the plate rim; where note, that if the height (1000
parts) is found so numerous as to create confusion, let 100 parts be
assumed; when the _length_ of the plate will become 26.8 or 26 and 8/10
instead of 268, and the operation will be so much the more simple.
It should be added that this process admits of being further simplified:
since the product of 11 inches, radius of the plate rim, multiplied by
268 (tangent of 15 degrees, or _length of the plate for a wheel equal in
diameter to the plate rim_) since this product, I say, is a _constant
number_, namely: 2948--which, divided by the _half diameter_ of any
wheel, gives, at once the length of the plate adapted to that operation,
in parts of which the height contains 1000; or supposing the height to
be 100 only, this constant number becomes (nearly enough for practice)
295. In a word, on a height of plate of 100 _parts_, when wishing to cut
a wheel of 4 inches in diameter, I merely divide 295 by 2, and get for
_the length of my plate_ 147.5 parts of which the aforesaid height is
100.
It may possibly be suggested that this method of using _plates_ to
determine the obliquity of the teeth is a homely method, giving some
trouble in the execution, and leaving a certain degree of roughness in
that execution. The fact is allowed; but this method has the advantage
of a _very general_ application, which many a better looking apparatus
would not present.
Besides, for _most_ uses, these teeth require chiefly that the obliquity
should be correct, and _not_ that the surface should be licked like
those of a gewgaw. In fine, the principle of this Machine once known,
its best form will occur to the reflecting mechanician according to the
_quality_ of the work he has in view: And in fact, in the hands of a
well known _artist_, this form has been already varied so as to produce
effects much higher wrought than could be drawn from the Machine above
described: which latter however in point of generality, still preserves
the advantage.
OF
A DOOR-SPRING,
_To keep a Door strongly closed, yet suffer it to be opened easily_.
That “necessity is the mother of invention,” is a remark none the less
true, for having become a trite proverb; I could mention the time,
place, and circumstance which gave birth to this little Invention: but
such detail would be superfluous. A certain door was, and is still, most
inconvenient, from the stiffness of the spring, and the noise it
occasions in a place where silence ought to prevail: which state of
things suggested to my mind the Machine represented in fig. 5, of plate
17.
_A B C_ in that Plate, is a horizontal section of the door, door jambs,
&c. The door spring now in use, is a barrel-spring, with an arm carrying
a small roller which presses in a gutter-formed plate, screwed to the
door. My door spring is on a different principle. The roller is fastened
in and by a small frame to the door, and the arm is fixed to the axis of
the spring, which passes up through the top of the barrel. This spring
is _much_ weaker than the former, insomuch as only just to close the
door by its elasticity; but when the door is shut, there is a sharp bend
in the arm that wedges itself against the roller, and _decuples_ at
least the force of the spring, as tending to keep the door closed. When
therefore it is desired to open the door, by pressing the door itself,
a good push is necessary, but only for an instant: for as soon as the
bent part of the arm is forced off the roller, there remains only the
small resistance of the spring to be overcome; which latter, when
suffered to act in shutting the door, will _not_ shut it with that noise
a stronger spring would occasion; and yet, when arrived at its first
position, it will keep the door as strongly closed as ever. And should
it be wished to avoid the necessity of pushing hard against the door,
even at first, there is a sliding button and stem _B_ put through it,
which, if pressed from the other side, with the force only of the
spring, will raise the latter beyond the roller, and thus open the door
with perfect facility: and this same process will take place in pulling
the door open by the hook _D_ from the inside: yet still the door when
closed will be as firmly so as before; the spring-bar acting in the
latter position, as much like an invincible _stay_ as the workman shall
have desired--this property depending clearly on the _nearness_ of the
bend to a right angle.
This device may appear to some an object too inconsiderable to be justly
dignified with the name of an invention. But if I should sometimes fall
into such an error as this, I intend to compensate for any thing too
trivial by giving in other cases, Inventions of ample size and number. I
might even mention the Cutting Engine given in this part, where several
Inventions are compressed into one, or rather presented as _one_, of
which several examples will occur.
OF
A DRAW-BENCH,
_For making my twisted Pinions_.
The pinion wire of clock and watch makers is well known. I am not wholly
acquainted with the manner in which it is drawn: but I have made my
pinion wire, of brass, in lengths of about a foot, by the Machine
described below.
A common Draw-bench (not here represented) is worked in the usual
manner: but the instrument which forms the pinion (see Plate 17, fig. 1)
is of a peculiar construction. It consists of a plate _A B_,
containing--1st. a guide tube _a_, (fig. 2) to centre and conduct the
blank wire;--2d. a ring _b c_, with _nine_ grooves cut on one of its
surfaces, directed to the centre, and in which are _well_ fitted the
cutters 1 2 3 4 5 6 7 8 9; and 3d. a ring _d e_, formed into nine
spirals exactly like each other, answering to the cutters, and destined
to urge them _equally_ toward the common centre whenever this circle _d
e_, is turned by the endless screw _C D_, in the direction of the arrow.
In fig. 2, _f g_ is merely a top piece to cover at the same time the
cutters and the ring _d e_; which latter is thus duly centered. The
points of the cutters 1, 2, 3, &c. are formed like the spaces of pinion
teeth; and in the other direction, are sloped 15 degrees to the common
axis, as taken at their pitch line.
The third figure represents the drawing clams, or pinchers, with a piece
of blank wire _d_ in them, tapered off to give easy entrance to the
cutters. These clams have a cylindrical part of about a foot long, in
which is cut a winding groove _a b_, whose use is to _turn_ the wire in
the act of drawing; for which purpose also the _swivel_ _e f_ is
provided. The method I employ to _trace_ this groove to the obliquity
required, is to measure the circumference of the cylinder, and call that
268; and then, to make its length, in the cylindrical part, equal to
1000 of the same divisions. But this is right, _only_ when the _pinion_
to be drawn is of equal diameter with the clam-cylinder _a b_: so that
if it is wished to draw pinions of a smaller diameter, I further say:
diameter of clam-cylinder _is to_ diameter of pinion, at the pitch line;
As 1000 (present length of clam-cylinder) _is to required length of
ditto_. Thus, for example, if the diameter of the pinion were only 1/4
that of the clam-cylinder, the _length_ of the latter would be only 250
of the 1000 divisions, before found: and so in proportion for smaller
diameters.
The figure shews this groove receiving a guide screw or stud _a_, which,
placed in the fixed headstock _a c_, turns the clams _d_, with the wire,
just enough to give the teeth an inclination of 15 degrees, thus
adapting them to the wheels of which the proportions have been already
given; where note, that the real dimensions of this pinion Machine are
_twice_ as large as those of the figures 1 and 2: but the size of every
thing is of course _variable_, according to the pinions required to be
produced.
OF
A GEERING CHAIN,
_Formed to work in the Patent Wheels_.
This Chain is shewn in fig. 4 of Plate 17. The links are formed to an
angle, in the middle, similar to that of the wheels at their pitch line;
of which the obliquity, for the V wheels, is greater than 15 degrees;
since the thickness of the wheel, is necessarily divided between the
right and left handed slope. Be this slope what it may, the chain and
wheels must of course be alike, measured at the pitch line of the
wheels; and _then_, as the chain geers with a straight _line_ of
pinions, they work together without sensible friction on the teeth, and
with nearly the same steadiness of motions as wheels would work
together. Moreover, if the drum be of a pretty large diameter, its
action will likewise be nearly _equable_. The degree of precision
depends, however, on the fineness of the pitch, and the largeness of
diameter in the drum; since every chain bending round a cylinder _must_
form a polygon of a _greater or less_ number of sides, dependent on
these circumstances. I repeat then, that while the chain works on the
pinions in a tangent to them all, there is no necessary friction between
them; nor yet on the pins of the chain, but only at the drums which
actuate and return the latter:--I shall dismiss the subject, by
observing, that I have used the term _drum_, because of the similarity
of this chain-motion to that produced by bands, where drums are
generally the _movers_. But here, this supposed drum is a wheel of
proper diameter, cut into teeth similar to those of the pinions; and
placed at the same height on its spindle. I have reason to think that
this chain, carefully made, would be an useful addition to the _bobbin
and fly frame_, applied both to the bobbins and spindles, instead of the
bands now in use; which, though a convenient resource, give a result
equally uncertain and imperfect.
OF
A SERPENTINE BOAT OR VESSEL,
_To lessen the Expence of Traction, &c._
The present description of this Machine, will consist, chiefly, of a
translation from my own specification, given at Paris with the
application for a _Brevet_, or Patent, obtained in the year 1795, and
which is thus introduced.
“It is a well-known fact, that the longer any Boat or Vessel is, in
proportion to its width, the less power it requires to convey a given
load, from one place to another. But these lengths cannot be extreme,
without introducing a degree of _weakness_, that would offer great
danger in the use of such vessels. If then a Boat of a given volume, be
divided into several long and narrow ones, the head of each adapted with
a certain exactness to the stern of its forerunner, they will (with the
trifling difference arising from the asperities of their surfaces) _all_
move through the water with the same ease as any single one; and carry,
unitedly, the same weight as did the large Boat before it was divided.
This idea constitutes the principle of my Serpentine Vessel.”
“This Invention is not to be considered as an imitation of the
well-known manœuvre of towing one vessel in the _wake_ of another: for
the resistance of the vessels thus towed, remains nearly, though not
quite the same as if drawn along separately. But here, by the adaptation
of the _prow_ of one Boat to the _poop_ of another, the first alone
suffers resistance from the water--which, although it enters between the
_joints_, strikes _only_ the first--and from this it follows, that the
_resistance_ of these vessels, in passing from one place to another,
_bears no necessary proportion to the weight they carry_.”
“Thus then, I obviate the necessity of having _broad_ vessels to carry
the heaviest burdens; for I disseminate the load over an indefinite
_length_: by which method also, my vessel rides in shallower water, and
depends less for its passage, on the state of the rivers or the seasons.
Besides, they require a much less number of horses, or exertion of
_power_, to transport a given quantity of goods; admitting at the same
time, a greater swiftness of motion. And finally, if these vessels
travel through different towns on the same voyage, the goods of each
town may be lodged in the same _part_, and merely detached in passing,
so as to lose _no_ time in unloading them.”
“Fig. 1 of Plate 18, shews the _plan_ of several forms which I give to
the articulations or separate parts of these vessels: so as to connect
them strongly, yet leave them, as a whole, in some degree flexible. The
form _A B_, is, for the first boat, a straight line across to form the
_stern_, and for the second an obtuse angle terminated by a semi-sphere
or vertical semi-cylinder, which enters a hollow and similar figure in
the first Boat--which latter, in this case, forms the _Head_ of the
whole Serpentine Vessel.”
“These two parts or joints, of which we have been speaking, are held
together by a rope _c d e f_, which, fastened to the second part at _c_,
passes over two pulleys _e d_, in the head, to the small capstan _f_, by
which, both parts are bound together as tightly as may be judged proper.
If it were thought necessary, the spaces _A B_ might be underlined with
a piece of leather or metal, _not_ to prevent the water from entering
between the Boats, but to prevent its _striking_ those which follow the
others through the water--a precaution less urgent in the other kind of
joint we are about to describe.”
“_C D_, in this same figure, presents another form of the head and stern
of two contiguous Boats or _parts_; (which, to save room, are both
supposed to be _broken off_ at some point between their ends:) where as
in the former case, the Boats are connected so as to remain horizontally
flexible. These forms are semi-cylindrical, the stern concave, and the
_head_ convex, to the same radius; and the motion takes place around a
bolt and pulley _p_, reeved with a rope coming from one side of the
first Boat near _C_ and led again to a small windlass or capstan placed
on the other side near _D_. _E F_, is another modification of the same
kind of joint: the centre of which is a bolt or stud _q_, (better seen
at _q_ in the 2d. figure) over which a triangular frame falls from the
preceding Boat, and thus connects them instantaneously; leaving a
certain flexibility in the horizontal direction.”
“Finally, _G H_ shews a simple mean of connecting these Boats, on the
supposition that both ends of each are formed alike to an obtuse angle
in the middle of their breadth. It is a kind of hook _r s_, mounted in a
frame turning on centres in the _preceding_ Boat, and reaching over into
the succeeding one; where it finds a hollow _step_ of metal which
receives and fits it, so as to hold these neighbouring Boats with
sufficient tightness, but still with a certain degree of flexibility.
Many other methods might be suggested, by which to form these joints;
and almost _any_ might be made to answer the purpose. I shall therefore
leave this branch of the subject, observing only, that the second figure
of Plate 18, is an _elevation_ of the same things: which, generally, are
marked with the same letters as far as they are visible.”
“The third figure presents the same objects in perspective; to which are
now added _two_ masts _I K_, placed obliquely on that Boat which forms
the Head of the whole vessel. This obliquity is useful when the boat is
drawn from one side only; but is injurious where the traction takes
place indifferently on both sides: so that I should not, _now_, advise
the use of this method--which indeed, I have avoided in fig. 4 of this
Plate.”
“In every case, each of the masts carries a pulley near _I_ _K_, over
which passes a rope, the ends of which are fastened to the masts by
proper brackets, near the deck: and to the middle of this rope is
fastened the track rope _L_, by which the horses draw the Boat along. By
these means the vessel is _steered_ either to or from the land: for if
the knot of the track rope is brought near the mast _I_, the Boat (which
as before observed is the head of the whole vessel) veers towards the
horses; and the contrary when the knot is drawn towards the mast _K_:
both which effects are rendered the more prompt and decisive, by the use
of the _lee boards_ _K M_, the nature and use of which are already fully
known.”
“But there are cases in which, from its great length, this Serpentine
Boat would require a particular direction, for some intermediate point
between its extremities; as although, in theory, every separate part
ought to pass through the same water, yet in canals or rivers much bent,
_this_ may not invariably take place; and _then_ a rudder would be
useful, even in the middle of the vessel. I have therefore placed a pair
at _P R_, fig. 3. Their motion is a vertical revolution, round a
horizontal centre; and as they are formed obliquely to the sides of the
Boat, when one of them is plunged into the water, it tends to drive the
Boat in a sidewise direction: and if at any time it should be desired to
stop the whole vessel, _both rudders_ would be plunged at once into the
water, when they would greatly contribute to that effect.”
“The fourth figure in this Plate 18, presents a general view of the
vessel, comprising five articulations, (or Boats) besides the head and
stern--which latter would fit each other without any intermediate parts,
and form a Boat alone. Nor do these five parts by any means limit the
useful number: but the Plate would not have contained more, unless on a
scale too small to be distinctly understood.”
“Returning now to fig. 1, we observe the ropes _A D F H_ and _B C E G_,
which are supposed fixed to the stern Boat, and carried to the capstans
represented in the _Head_. These ropes consolidate the whole fabric, and
act, occasionally, as a kind of _muscle_, to govern the larger
evolutions. These ropes pass in the brackets placed near the joints _A
B_ and _C D_, &c. being _under_ the gang ways, of which a portion
appears at _S_ fig. 3, hung upon hinges, that they may be turned up when
the Boat is used in narrow water.”
To the above specification were added the following remarks, which still
apply to this kind of vessel, navigating on canals and inland rivers:
“this vessel admits of the use of every kind of _mover_; such as men,
horses, wind, or the steam engine; the latter of which I propose to
apply to it in a manner equally simple and effectual; especially so as
_not_ to injure the banks of any canal, &c. by acting against and
disturbing the water.”
I need not repeat that this Invention dates as high as 1795: as the
_Brevet_ was issued in that year. It may be added that four _parts_ of
such a Boat were executed about the same time; namely, the head, the
stern, and two intermediate _pieces_: making together a length of 100
feet; and these, loaded to a certain depth with stones, were drawn _up_
the river Seine by a single horse _on a trot_--which would likewise have
taken place had the Boat been ten times as long; since, as before
mentioned, _the resistance of this kind of vessel bears no given
proportion to the Load it carries_.
OF
A MACHINE
_For destroying, or lessening Friction_.