Part 16
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.
OF A MECHANICAL ESSAY, _To derive Power from expanding Metals_.
It is not supposed that this Essay can lead, immediately, to any result of magnitude; but it is thought to be a subject capable of further extension, and thus, finally, of future usefulness. Were this process only sufficient to supply a single house with water, at a small expence, the labour bestowed on it would not be altogether in vain.
By General Roy’s experiments, cast iron (and steel) expanded by 180° of heat (or, by passing from the freezing to the boiling point of FAHRENHEIT) 0.013 of an inch per foot.
Supposing, then (Plate 34, fig. 1), the tubes _A B C_ to be 20 feet long, their whole expansion will be 0.26 hundredths of an inch. But, as the tubes are placed in the figure, the _half_ tubes _A D B D_ act together on the sphere _D_, and, both together, drive it in the direction _E D_, _more_ than as the above expansion, in the proportion of the line _E D_ to that _A D_. Taking, then, one half only of the above expansion = 0.13 hundredths of an inch, _that_ must be augmented in the ratio of the sine of 60 degrees to radius, or in that of _A D_ to _E D_. I, therefore, multiply this decimal 0.13 by the fraction 1000/866, which gives 1300 to be divided by 866, or very nearly 0.15 for the expansion, in the direction _E D_, occasioned by the two half bars _A D B D_: and the same is true at the other angles _F_ and _G_.
Again, to find the expansion (and _contraction_) of the bars _a b c_, we must compute their length as compared with the half tubes above-mentioned; and that length is to 10 feet (the half tube _A D_ or _B D_) as 866 is to 1000 = 11.54 nearly: the expansion of which is thus found:--if 10 feet expand 0.13, what will 11.54?--Answer, 0.15. Now, as the machine acts by the _heating_ of the pipes _A B C_ simultaneously with the _cooling_ of the bars _a b c_, we must add the former expansion to this _contraction_, which gives us 0.30, or _three tenths_ of an inch for this combined effect at the three angles of the Machine. And, _supposing_, now, any pair of bars to act directly against each other, as at _H I K_; and that, further, the bars be stretched until the angle with the horizon be only 2 degrees, then the vertical motion at _I_ will be to the horizontal (arising from the expansion aforesaid) as 1000 to 35, the sine of 2; that will be, in round numbers, 28 times as great, or 28 _times three tenths of an inch_ = 8.4 inches, which is the _stroke_ of this Machine in these dimensions.
In this calculation, I have not forgotten that the vertical and horizontal motions are _nearer alike_, when the bars are not drawn so tight at _K H_; that is, when the joint _I_ is lowered. But it is equally true that, when the joint _I_ rises still more, the difference between these motions is _still greater_; so that, as a medium effect, I think we may reckon on an _eight-inch stroke_ in the present case.
The question now recurs, of what _strength_ are these strokes? Are they sufficiently powerful to produce a useful effect with so _short_ a motion? This I cannot say from experience; but, from the known strength of iron and steel, their power, in these dimensions, must be _very great_. A few more observations may occur in the course of the enlarged description we shall give of the Machine itself.
_A B C_ are three pipes of cast iron, well turned at the end, and having conical points of iron, well steeled, let into them, so as to have no tendency to _bend_. _a b c_ are three steel bars, placed in troughs, so as to be heated or cooled by water poured into the latter. Or, these troughs _may_ be exchanged for tubes, to admit heated or cooled air, according to the means used to cause these mutations. In a word, although I have represented these bars as contained in troughs, I intend to finish my description, on the supposition that they are _tubes_, because I intend to suppose the Machine worked by _air_ instead of water.
To proceed: at _d_ is an opening _under_ the tube _B_, into which air enters, and _C_ is an opening _on_ the top of the tube which emits the same air, the three pipes being made to communicate by means of a short junction-pipe at each of the angles _D_ and _G_. Here, then, the fire-place _f g_, fig. 2, must be noticed: the use of which is both to heat and cool the Machine; and the following are the means:--This little instrument contains fire in it’s middle compartment, and that fire draws _air_ into the part _f_, and drives it out of the part _g_. It also _turns_ on a centre-pin, seen in the figure. This chaffing-dish, then, is placed at _i d_, and there serves a double purpose. When it’s pipe _g_ conveys heated air into the pipes _B A C_ (and _out_ at _C_), it heats those pipes and expands them; but, at the same time, the pipe _f_ of this instrument draws cold air through the three tubes _a b c_, in which are the steel bars that require to be _contracted_: both which operations conduce alike to the above-described effect. By these means, the weight _w_ is raised, and (for example) water sucked into the pump _X_. But, turning the fire-place half round, we reverse this effect. The _hot_ air is now drawn, out of the pipes _A B C_, and _cold_ air drawn through them, by which they are _cooled_; while the hot air, from the fire, is thrown through the pipe _g_ into the tubes _a b c_, and passing through the chimneys _k l_, there heat the bars and expand them,--both which operations concur in _letting down_ the weight _E_, and thus, in forcing the water of the pump to whatever destination was previously assigned it.
OF A MACHINE, _For Making Laces, Covering Whips, &c._
Many people, in these parts, have seen a certain machine, said to have been invented by an inmate of that laudable institution the Liverpool Asylum for Blind People; for the purpose of making laces, covering whips, &c. I hope the similarity of name will not induce any reader to suppose that I have had that machine in view, and am endeavouring to cast it into the shade, or purposely to supersede it. If any person should thus think, I have a _safe_ reply at hand. My own invention (somewhat less perfect than it now is) was made, many years ago, on purpose to serve _an Asylum for the Blind in Paris!_--a reflection with which I shall, at once, close this, perhaps, unnecessary apology.
This Machine is represented in Plate 34, at figs. 3 and 4. It consists of a frame of wood or metal _A B_, on which are _mounted_ the following objects:--1st, on the traverse _B_, a fixed tube, having for it’s base the horizontal plate _a b_, and rising perpendicularly to _near_ _c d_; where it unites with a conical or trumpet-like vessel _c d_, _f e_; the left side of which is shewn in perspective, and the right side in a section only. To this _fixture_ is adjusted the spherical portion _g h_, _h_, prepared to receive several cuts or slits 1 2 3 for the bobbin-slides hereafter-mentioned, to slide up and down in. This leads us to observe the upper fixture _C_, which is a cylinder, terminated downward by a spherical _dome_ _i k_, _k_; also receiving the several cuts 4, 5, 6, into which the aforesaid bobbin-slides pass from the former slits 1, 2, 3, &c. Now it will be seen that the two spherical parts thus fixed, are separated from each other by the circular and horizontal slit _l m_, whose use is to permit the _pipes_ shewn in the section at _n o_, to circulate _all round the machine_, while the bobbin-slides and bobbins _k p_ are sometimes _above_ and sometimes _under_ the said slit _l m_.
Now, then, it becomes necessary to speak of the _cause_ of this passage of the bobbin-slides from the under to the upper parts of the slits 1, 4, 2, 5, and _vice versa_. That cause is in the second dome _q r_, which covers, as far as it rises, the inner dome _f i_, _k h_; and it consists in a serpentine canal, of which a section is given to the left of _q_, and at _s_, _in the section of the principal figure_.