System of Toothed Wheels, as described in this work, has met with--not
intending to speak of the local difficulties I experienced at a former
period. But, _here_, the interests of truth force me to break silence.
The necessity I stood under of bringing out this work in Parts, has, at
least, had one advantage: it has given me an opportunity of watching the
workings of prejudice--not to say of envy,--and thus of neutralizing, in
some degree, the effects of either: from which, however, I claim nothing
but the _right_ of making my labours the more extensively useful, by
making them better known. I have, then, to say that, among _a few_ other
objections to the System, _this error_ has come from so respectable a
quarter, that it would be unjust to Science, and injurious to truth, to
let it pass unrefuted. It has been said, that “my wheels are a Chinese
Invention;” and _this_ proof has been adduced of it--namely, a
sugar-mill, from China, having it’s cylinders _fluted in a spiral
direction_. Now, the fact is, it would have been difficult to give a
better proof that the wheels are NOT a “Chinese Invention;” for two
inventions are then only alike when they produce the same effect, by
similar means. But here the effects intended are totally different. A
sugar-mill acts in or near the plane of the centres; and one of it’s
cylinders is not intended to drive the other independently of pressure
between them. This is so true, that the rollers of many sugar-mills are
not fluted at all. Besides this, my wheels exert no pressure in that
direction; and if they did, they would not be cog-wheels. In a word,
their action is _at right angles to the former_, and has an object of
quite a distinct nature. These, then, are by no means the same machine;
and, therefore, mine is not a “Chinese Invention.”
Here, however, I _beg_ not to be misunderstood! I should feel no regret
at appearing on the mechanical stage, a few hundred years after so
ancient and astonishing a nation as the Chinese! But, in this case,
truth did not permit me to sanction, by my silence, this flagrant
error.
Finally, an opinion exists, _somewhere_, that these wheels _will_ never
be generally used, from the difficulty of making them; and this opinion
has been expressed, apparently, with no very amiable feeling. But,
amiable or hateful, the opinion is highly erroneous! It is so far from
fact, that, in a competent manufactory, they can be made more cheaply
than others now are; and _many_ persons are already calling for them
from every quarter; nor is any thing wanted to insure their immediate
prevalence but a _common_ degree of commercial energy.
PART FOURTH.
A NEW CENTURY OF
Inventions.
OF
A CUTTING ENGINE,
_For large Bevil Wheels and Models, on the Patent Principle_.
One of the most prominent subjects of this essay, if not the most
important, is the System of Toothed Wheels, with which the second and
third Parts were introduced, and which still claims a share of my
readers’ attention. As hinted a few pages backward, it seems not enough
for me to exhibit and describe the System, but I must defend it against
repeated objections, on pain of seeing it’s utility delayed, and the
public deprived of it’s real and solid advantages. I am _far_ from
wishing to impeach the _motives_ of those who still nourish or express
dissent, when they deign to bring reasons for so doing; but the mere
opinion--“it won’t do”--expressed by a man of reputation, may impede,
for a time, the progress of an useful discovery, and thus produce a
public evil. This, then, is a result I am anxious to avert; as the
present System _has_ many points of excellence, against which no
insuperable objection _can_ be brought. Had I not declined, already, to
name either the friends or enemies of the System, I might here appeal to
persons who highly approve of it; and, indeed, who use it daily with
manifest advantage. But, I forbear. If, by means of the Engines already
given, and _that_ I am going to offer, it is proved, that the difficulty
of making these wheels is _trifling_, compared with their utility, one
important point will be gained: I shall not hear it repeated, “that the
System cannot succeed, _because of the difficulties of it’s execution_.”
The present Cutting Engine is shewn in figs. 1, 2, 3, of Plate 32. It’s
immediate use is to form the teeth of _wooden models_, for casting.
These are previously _built_ as usual, and _lagged_ with _bay-wood_, of
sufficient thickness to furnish the teeth, and leave a small thickness
of _that_ wood behind or under them.--_A B_, in fig. 2, represents a
wheel of this kind, ready for cutting;--mounted correctly on the centre
pin _C D_, which latter is so formed as to be _fixable_ in any position
on the table or bench _E F_. Under the wheel _A B_, there is a kind of
_index_ _a b_, put upon the said centre pin _C D_, which, by means of
the clamp and screw _b c d_, can be occasionally connected with the
wheel _A B_ so as to turn it, when it is itself turned by the means
hereafter to be mentioned. To proceed with the description: _G_ is a
slide, moving horizontally on the bench _E F_, as seen at _f e_ fig. 3;
this slide being the basis of the headstock _G H_, which contains the
_perpendicular_ slide _H I_, itself the support of the cutter-frame _K
L_, so constructed as to turn on it’s bolt above _I_, and take any
proper position over the edge of the wheel or model _A B_. This slide,
then, with it’s appurtenances _H I K L_, moves along the bench _E F_, as
seen in fig. 3 at _f e_: and what gives it this motion, is, the screw
_g_, furnished, purposely, with a left-handed thread, working in the
_half-nut_ contained in the small frame _h_, which contains also a
jointed _cap_, that can be lifted off in an instant, and the screw set
at liberty. Moreover, the second use of this screw _g_, is to _be_ thus
disengaged from it’s nut, and lifted up to about _i_, where it serves to
push back the slide _G_ towards the wheel, without that loss of time it
would occasion if pushed back by the working of the screw. The letters
_M N_, shew another important part of the Machine, applying to the
cutting-process. It is an inclined plane, sloped to the same degree as
the bottom of the teeth of the wheel. (See the line _a k_.) This
inclined plane, then, is fastened, in any proper place, on the bench _E
F_, by the wedge _N_, _just_ like the puppet of a common turning lathe;
and it passes through an opening in the slide _G I_, or rather suffers
this to pass _over it_, as better seen at _M_, fig. 3. Furthermore, the
slide _I_ (fig. 2), after gliding down this inclined plane _M G_, will
have to be raised between each cutting: and that is the office of the
workman’s hand acting on the lever _O P_, through the iron frame _Q M_,
which is shewn at fig. 3, in another direction; and marked with the
letters _Q l m_. In fine, the slide _G_ carries on each side of the
Machine a pulling bar _n_, connected with the said slide, and with a
smaller sliding piece _o_, the use of which is to hold a pin (seen in
the figure, but leaving no room for a letter of indication), which
_turns_ the wheel _A B_, by the plate _p_, as the slide _G_ recedes, and
the cutter-system _I K L_ descends on the inclined plane
before-mentioned. Having thus adverted to all the important parts of the
Machine, we turn to fig. 1, for the purpose of shewing _what_ the plate
(whose edge is seen at _o p_) means; and the effect it is intended to
produce.
In that figure, let _B A c_ be the section of any wheel it is desired to
cut on this principle. The width of the face of such wheel is shewn by
the line _a b_; and _a c_ is called the _projection_ of that face, on
the base of the cone of which the wheel _A B_ is a portion; it’s summit
being at _C_. The line _e d_, shews _one_ of the spiral teeth with which
the wheel is to be furnished; and I make it by this uniform process: The
pitch of the wheel, whatever it be, is set off from _e_ to _f_: and that
pitch is divided into _eight_ parts, (shewn here as _four_ on account of
their smallness) while the width of the face _f d_, is divided into
_nine_ parts, shewn here (for the same reason) by _four and a half_
divisions. This latter division is more numerous than the former, that
the principle may be a little _overdone_; or that the teeth may overlap
each other by 1/9 of the pitch: To which purpose, beginning the spiral
line _e d_ at _e_, I move in the second circular line from _e_ to the
second radial line _C i_, and draw _that diagonal_ which forms the first
part of the curved line _e d_. From this second point, I go to the third
circular line, taking also the third radial line, and drawing the
diagonal. This I do until arrived at the fifth circular line, when I
find myself likewise at the fifth radial line _C d f_. These four spaces
thus gone over, represent the eight parts into which this part of the
face _a b_ _would have been_ divided, had the figure been larger: and
there remains a small division near _d_, equal to one half the others,
through which the curve _e d_ is prolonged by a similar process; and
this latter portion is what the successive teeth _overlap_ each other,
as before stated.
Now, it will be seen below, that the needful _circular_ motion is given
to this wheel, by a movement that takes place in a direction parallel to
the base _a c B_ of this figure. The curve _e d_, must, therefore, be
transferred from the surface of the cone, to this base _a c B_. To do
this, I place a point of the compasses at _A_, and trace, with the
openings _A a_, _A c_, &c., the six _quadrants_ included in the space _a
c g h_, which are now the projections, on the base, of the circular
lines _a b f d_ on the surface of the said cone. Here, a slight
difficulty should be obviated: strictly speaking, this _projection_
would be horizontal, and, of course, invisible in this position of the
wheel. But I have supposed the figure _a c g h_, turned ninety degrees
downward, round the horizontal line _a B_, so as to make one
representation suffice; and also to shew the connection of the lines _a
b g h_, with those _f d a b_. The curve _k l_, is thus a _copy_ of that
_e d_, only _shortened_ in the proportion of _a b_ to _a c_--that is, of
the side of the cone _a C_, to the half-base _a A_.
To secure, then, the coincidence of the pitch, as set off on the
circumferences _a f_ and _a g_, we must divide a similar portion of both
into an equal number of parts, _e f_; and treat them, on the lines _a c
g h_, as we did on those _a b d f_; by which means we shall get the
curve _k l_, _the projection of that_ _e d_. And this curve _k l_, must
be made part of a _plate_ _k l m n_ (about 1/10 of an inch in
thickness), the use of which is as follows:
This Plate _k l m n_, is no other than that marked _o p_ in fig. 2; and
it is there fixed to the index _a b_, directed to the central pin _C D_,
as it is in fig. 1 to the centre _A_--insomuch, that the _pin_ shewn in
fig. 2 near _o_, acting on the _sloping_ curve _k l_, will turn that
index (and with it the wheel) by the very motion which draws back the
slide _G_ (fig. 2), and lets down the slide _I_ on it’s inclined plane
_G M_.
We may remark, lastly, that as the present Machine is adapted to _large_
models, it is not, now, provided with a dividing-plate, although the
means of so doing are self-evident. On the contrary, the division dots
are seen on the edge of the wheel _A B_, as is likewise one dot, near
_b_, on the clamp _b c_, from which a given distance is set off to each
of the dots on the wheel, so as to give the pitch required. By these
means, then, the wheel is divided and cut, in _good_, if not in
exquisite divisions; and all the teeth take their shape from the Plate
_o p_ (or _k l m n_ of fig. 1), and are thus good, in that respect also.
To recapitulate the steps of this process--The workman stands behind the
Machine, near _E_; and, working the screw with his right hand, draws
back the slide _G_, (the _power_ then turning the cutter _r_ very
swiftly) by which means, the slide _I_ glides down the inclined plane
_M_, and the cutter, impinging on the sloping face of the wheel, cuts it
to the depth _r a_; the shape of the tooth (by the turning of the wheel)
being the spiral form _e d_ of fig. 1. It may be added, that the lifting
lever _O_ permits this descent of the bar _Q M_, because it is suffered
to fall lower than _now_ represented. Thus, when the slide _G_ is
arrived near _h_, the tooth is finished; and the cutter leaves the wheel
at _a_: after which, the cutter-frame and slide _I K L_ are raised by
means of the lever _O_--the screw _g_ taken out of it’s _steps_, and the
slide _G_ pushed back by it, until the vertical slide _I_ rests again on
the inclined plane _M_, as it at first did. Nothing, now, remains to
prepare for cutting a new tooth, but to change the division-dot, by the
application of the gauge or compasses, from _b_ to the next point on the
wheel; to do which, of course, the clamp _b c_ must be loosened and
refastened by the thumb-screw _d_. I would just notice the 4th
figure--to say, it is a sketch of one quarter of a bevil wheel; intended
merely to shew the form and position of these teeth, and the general
appearance of the System.
Finally, my readers will please to advert to what has been already said
on the _forms_ of these teeth, and their uses: and recollect especially
what was observed on the epicycloid, as applied to them. It will easily
be perceived, that to _put_ that form on one of these teeth would be an
almost hopeless attempt!--and, happily, it is not necessary. We can,
however, by using the cutter _r_ with various slopes, and going several
times through each _space_, cut _facets_ on the teeth, quite near enough
to the theoretical form to make them work _well_ together; and, as
before observed, nothing is wanting to make the teeth _perfect_, but to
run them together with the wheels placed in due position.
OF
A CENTRIFUGAL DASH-WHEEL,
_For Bleachers, Dyers, &c._
To form a true estimate of the value of any new machine, it is necessary
to examine the nature and operation of those that have been used before
for similar purposes. And this is the more needful here, because the
present _Dash-wheel_ is essentially good, both in it’s properties and
effects. The only room left for improvement, seemed to respect the
_quantity_ of work done by it: and this is, the chief point of
comparison we shall establish in what follows:--
The third figure, in Plate 33, is a sketch of the common Wash or
Dash-wheel. The pieces of calico (or other goods) are put into it
through the round holes, dotted in the figure; and, by the revolution of
the wheel from right to left, are carried up from _a_ to _b_, or nearly
so; from whence they drop by their weight to _about_ the point _c_,
where they meet the angle formed by the circumference of the wheel and
one of the four arms or partitions, by which it is divided. If the wheel
go too fast, the line of falling becomes more like the curve _b d_, and
the goods strike the circumference too high, and in an oblique
direction;--whence the blow is reduced, and the washing becomes
imperfect. If, on the other hand, the wheel move too slowly, the pieces
_slide_ down the ascending partition (_a_) before it comes to the
vertex, and thus only fall from the axis to the lowest point of the
wheel;--whence, also, an inefficient stroke. Thus, do these wheels
require a moderate velocity: and they are reckoned to do their work best
when making from 22 to 24 turns, and giving, of course, four times that
number of strokes per minute.
The produce of these wheels is thus circumscribed by a _natural_ cause
that cannot be altered--namely, by the law of falling bodies; and my
Invention has in view to _elude_ the shackles which confine this
process, and to produce a much greater effect in the same space,--the
same time,--and with the same expence of workmanship.
To this end (see figs. 2 and 4, of the same Plate) I place two, four, or
more boxes _a_, _b_, _c_, _d_, on as many wheels _e f_, toothed on my
Patent principle; the latter, in the present case, being about two feet
in diameter, and the boxes, in length, three quarters of that diameter:
and of _any_ convenient _width_, according to the size of the pieces.
The wheels _e f_ are mounted on the strong shafts _C D_, which run,
below, in the wheel _E_; and by which, also, they are turned round the
common centre, by means of the vertical wheel _F_. Further, in the
centre, and between the wheels _e f_, I place the bevil wheel _i_, of
half the diameter, in which the main shaft runs loosely, and which is
itself fixed to the upper frame work, so as not to turn at all. The
three _Patent_ teeth at _e i f_ shew that these wheels are to geer into
each other on that principle: and it is likewise seen that this whole
mechanism is included in a set of rails, of an octagonal form, for the
purpose of preserving the men from danger, while in the act of charging
and discharging the boxes. And here it is worthy of _some_ remark, that
this process must be _easier_, and more quickly performed, with these
_open_ boxes, than through holes made in the _vertical_ side of a
Dash-wheel, on the usual principle.
To account, now, for the sloping position of the shafts _C D_, and the
consequent slope of the boxes, they are thus placed, in order that the
goods may not drag too much on the bottoms of the boxes, when passing
from one end of them to the other. Instead of this, they are, in fact,
_thrown_, by the centrifugal force, from the inner angle _h_ (fig. 2) to
some point _k_ up that side of the box which is then outwards; where
they strike, and then _fall_ into the contiguous angle under _k_, to be
again projected thence, after one revolution round the common centre;
for, it should here be remembered, that, by the given proportion of the
wheels, the circulating wheels _e f_ turn on their own axes exactly one
half round, for every whole revolution round the common centre _A B_.
To elucidate this still further, I have outlined, at _A_ fig. 1, the
central wheel _i_, of fig. 2, together with _one_ of the excentric
wheels _B_, and the lines _a b_, _a b_, &c., representing the boxes,
are _supposed_ to be wires with the balls _b b_, &c. sliding on them, as
is usual in some experiments on the _Whirling Machine_--(See “FERGUSON’S
LECTURES,”) Of these _wires_, I have given the true directions in 12
positions of the wheel _B_: the epicycloid _b b b_, &c., shewing the
steps by which the ball _b_ is brought _toward_ the common centre,
during _three quarters_ of the revolution; and also the position of the
wire on which it slides: where it is evident that the ball _b_ has a
tendency to preserve it’s station, at the _first_ end of the wire, until
the latter takes the position _b b c_, when it forms (or nearly) a
tangent to the curve, and is, at the same time, at right angles to the
_radius of motion_, _A b d_. From this moment, then, the ball is free to
leave the centre, and to fly off in a tangent with the velocity with
which the curve itself is generated at that point. We might, thus,
during the rest of it’s flight, seek it somewhere in the line _b f g_;
but, as the wire _continues_ to change it’s position, and _must_ turn
half round on it’s own axis, by the time it arrives at _B b_, or
describes a quarter-circle on the common centre, it will again overtake
the ball--and, giving it a curvilinear direction, will finally carry it
to it’s other extremity, at or near the point _B_--where it’s motion
first began: and thus shall we give as many strokes to the ball, as
_half turns_ to the wheel _B_; or, in other words, as many _dashes_ to
the cloth, as we give turns to the boxes, round the common centre.
By this process, then, substituted for that of the common Dash-wheel, we
can increase almost indefinitely, the number of passages of the cloth
from one end of the boxes to the other; and the force of the _dash_ will
be as the squares of those numbers; since (as FERGUSON expresses it) “a
double centrifugal force balances a quadruple power of gravity.” If,
then, with four boxes we turn this machine 60 times in a minute, we
shall have 240 strokes in that time, instead of about 90 given by a
common Dash-wheel; and this difference might be more than doubled, if so
desired: for should, then, the stroke be found too severe, the boxes
might be shortened, so as to lessen it’s violence, though preserving all
it’s frequency.
There are _two_ other objects that present enough analogy to this
_Washing_ process, to be here mentioned. The first is the operation of
_Fulling_, as applied to woollen cloths in general. That process, I
fear, is not performed at present in the best manner possible; and I
feel persuaded that the centrifugal motion might be applied to it with
advantage--whether as to quantity of produce, or perfection of effect:
and having thus said, I shall leave the idea to the riper judgment of my
manufacturing readers.
The second object I shall just introduce is, that of _Kneading Dough_,
for bread, by the same centrifugal agency. It is well known, that an
ingenious _baker_, of Paris, invented, some time ago, a method of
_kneading_; which consists in letting the lump of dough fall
successively from the four sides of a square box, revolving on a
horizontal centre. As this idea seems to have succeeded _perfectly_, I
offer the Centrifugal System, as tending to quicken, almost
indefinitely, such a process; and I particularly recommend it to the
attention of Government, and of all _large_ establishments as a mean of
doing well and rapidly, _by power_, what is frequently done slowly and
ineffectually, by the usual methods. _Verbum sat._
OF
AN HYDRAULIC LAMP
_For the Table_.
I call this an Hydraulic Lamp, to distinguish it from the Hydrostatic
Lamps, commonly so named: and I think the distinction proper, because
this Machine acts in a different manner. It’s principle will be seen in
a moment, by turning to the 5th figure, of Plate 33. If, there, we pour
oil (or any liquid) into the bent tube _A D G_ at _A_, the first effect
will be to raise it to _C_, in the rising branch _B C_; and from _C_ it
will trickle down the branch _C D_, leaving _the air, there, to occupy
it’s own place_. Continuing to pour, slowly, more oil into _A_ the
trickling oil in _C D_ will ultimately fill the rising tube _E D_,
expelling the air before it; and, now, the weight to balance the column
in _A B_ will be _both_ the columns _B C_ and _E D_; whence, of course,
that column will rise as far above _C_ as _C_ is above _B_; that is,
half-way between _C_ and _A_. Here, _there would be_ a small deduction
to be made, if the height _B C_ were considerable; but, as it is only
supposed to be about a foot, the compression of the air in _C D_, &c.,
(being about 1/3 of a foot or 1/90 of an atmosphere) may be neglected.
Continuing, then, to pour oil into _A_, we shall again fill, _not_ the
descending tube _E F_, but the rising tube _F G_; whose column will thus
be to be added to those _B C_ and _E D_; so that now the column _A B_
will rise to _A_, and _there abide_, as long as the mouth _G_ is kept
full, or nearly so.
The above is the principle of the Lamp announced in the title; whose
effect depends, then, on the number of _bends_ made in the tube _A D G_,
which number (whatever be the _form_) it would be well to make rather
greater than smaller, as the height _B C_, &c., might be so much the
less, compared with the whole height of the column _A B_; by which
means, also, a smaller difference in the level of the column _below_,
would _return_ the oil necessary for the consumption of the wick
_above_.
I have given this idea what I think a better form in fig. 6. Instead of
the bent tube _A G_, of fig. 5, _this_ form supposes a series of
_air-tight cups_, embracing each other; one half of them with their
mouths opening _upwards_, and the other half with _theirs_ opening
_downwards_. They are shewn, by a section only, in this fig. 6; where _a
b c_, _c b a_, present the under cups, forming one piece with the outer
surface of the bottom vessel _d a c_, _c a e_: and, while speaking of
this part of the Machine, I would just indicate it’s cover _d e f g_ put
on like the lid of a snuff-box, and carrying a case or tube _f g_, the
use of which will be mentioned in a moment. To proceed, then, the upper
vessel is shewn by the edges of it’s cups seen immediately over the
_figures_ 1 2 3, 4 5 6, placed between the _letters_ _a b c_, &c.--These
inverted cups make also _one body_ with the moveable cover shewn between
_d_ and _e_, and to which is soldered the tube _h i_--which, sliding in
the case _f g_, keeps this inverted vessel steady. Where note: that
there is an _inner_ tube soldered into the tube _h i_, through which
alone the oil rises, and which can hardly be made too small, since it
has only to supply the consumption of a lamp--namely, a few ounces of
oil in a whole evening. We may, finally, take notice of the weight
placed _under_ _f g_, upon the said inverted vessel, and which helps to
counterpoise the oil in the rising tube _h i_; which tube, as before
observed, may be as many times _higher_ than the distance _a d_ or _e
a_, as there are rising columns between the cups _a b c_ and those 1 2
3, &c.
I am not wholly prepared to say what portion of the oil it might be best
to re-elevate by the pressure of the aforesaid weight _f g_; but, if it
were a considerable part of that contained in the central compartment _c
c_, _that_ column would be shortened in proportion; and the reservoir at
_i_ would, doubtless, feel the want of it to preserve it’s level. I
think, therefore, it might be well to use, below, a _cup_ or two more
than sufficient, so as to raise the main column higher than actually
wanted; and to coerce this rising tendency, by a small stop-cock in the
rising branch, to be _gently_ opened at the will of the person using the
lamp. I cannot say I have exhausted this subject; either in these
respects, or as to it’s technical capabilities. But I have fully _tried_
this method of raising oil above it’s level; and used, for some time, a
lamp made on this principle, and which is still in my possession: and,
at some future time, I intend to bring forward an Hydraulic Machine,
founded on the same principles.