Part 15

1st.--These objects are dropped into the vessel as soon as produced, and the vessel is filled, one half or more, with cold water from the reservoir _F G_. The things are then left to _steep_ in this bath for a day or two, or what space of time the periodical mutations of the house permit. By which operation _alone_, the miasmata are already much confined by the water, even though the lid of the vessel should be but partially shut: after which, this steeping operation may be continued, with the accompaniment of a few turns of the handle (_E_) to fully saturate every part of the mass. In the second place, a small stream of water is let through the cock _f_, and the wheel _C D_ is kept turning for a few hours, to discharge the cold water and the most offensive matter, through the cock _g_, into the sink: and, thirdly, the steam-cock _K_ is opened (that _g_ being shut), by which means steam is brought into the vessel _A B_, and the whole soon raised to the boiling temperature. This state of things is continued, as long as it is found necessary; the motion, of course, being also continued, and even accelerated, that the mass of objects may _fall_ from angle to angle, and be thus _well washed_--that is, well _finished_, if _plain_ things; and fully prepared for finishing, by hand, if of a nature to require close attention. And, finally, in many cases, the warm process may now be abandoned, and a new stream of cold water be injected, accompanied by a due motion in the vessel, so as to _rince_ the contents; and thus leave nothing to do for the laundresses, but to dry and mangle, or _iron_ them; where, it is plain, that no inconvenience can have arisen from this process, either to these persons, or to the other inmates of the house.--Hence, then, this Machine _has the properties announced--of confining the offensive matter until cleansed away_.

OF A MACHINE, _For propelling Boats, on narrow Canals, without disturbing the Water_.

The application of steam-power, to the motion of boats on narrow canals, is, I believe, much impeded by the consideration that the agitation of the water injures their banks, and would finally destroy them. On the other hand, it is known, that to drive a vessel, by acting on a fleeting medium, such as water, we must, at once, submit to lose about one half of the whole power employed--that is, the power, armed with energy enough to produce the required velocity, must go through twice the space that constitutes the _way_ or progress of the vessel. This depends, however, on the size of the floats or paddles employed, compared with the section of the boat, as modified by the form of the prow; but it is difficult to employ a paddle so large as to suffer more resistance from the water than the boat itself; and, if they are found _just_ equal, the _loss_ of power is exactly one half of the whole. These, then, are the two difficulties which I hoped to avoid, by the method now to be exhibited.

The idea is this--To have a large and heavy wheel _A_ connected with a _long_ shaft _B_, reaching from the boat to the shore, and, turning that wheel _in_ the boat, to propel the latter, by means of it’s rolling motion, on the bank or track-way; or, in some cases, on a proper rack, placed there for that purpose.

The Machine itself is represented in figs. 3 and 4, of Plate 31; fig. 3 being a stern-view, and fig. 4 a side-view, both of the machine and the vessel. _C_ is an axis, placed along the vessel, and turned by _any_ convenient power--as a horse, a steam-engine, &c. On this axis, considered as the _first motion_, are fixed the two bevil wheels _b c_, from which the long shaft _B A_ of the rolling wheel takes it’s motion. The use of the two wheels _b c_, is to drive the boat in the same direction on whichever side of the boat the wheel _A_ may be placed; for this, of course, must follow the track-way, which is sometimes to the right and sometimes to the left of the vessel.--Between the two wheels _c b_, is a sliding block (or catch-box) _d_, in which the shaft _A B_ of the large wheel has it’s lower pivot, and by which it’s wheel _B_ is almost instantaneously shifted from one to the other of the vertical wheels _b c_: the catch-box _d_ being itself _worked_ by a lever, of which the end only is seen at _e_, fig. 4. In fig. 3, there is further shewn a rope or _stay_ _f_, which, fastened to the socket _s_, of the rolling wheel _A_, and fixed in the middle of the boat, at the greatest possible distance from it, serves to keep that shaft at or near an angle of 90 degrees with the boat’s side: so that (the vessel being _long_) it becomes easy by means of the rudder, assisted, perhaps, by _lee-boards_ to keep the _way_ of the boat in a line parallel to the shore, notwithstanding the tendency to veer outward, given by the wheel _A_, while acting on a point so far from the body of the vessel.

I further observe, that, in order to shift the apparatus, with a certain facility, from one side of the boat to the other, there is a mast _M_ placed ahead of the mechanism just described, which rises as high as the length of the main-shaft (but can be _lowered_ to pass a bridge, &c.), and to the top of which is fixed the block _g_, through which a rope passes from the foot of the mast to the above-mentioned socket of the wheel _A_. By this rope the wheel is hauled up till nearly ready to fall over the centre; when a push from below will complete that passage; and the wheel _A_, being afterwards _lowered_ by the rope _h i_, will soon find it’s proper position on the other side of the boat, as before anticipated. Where, it should also be remembered, that this shaft must have a joint and socket, to permit it’s being bent, to pass a bridge, &c.

Hitherto we have supposed this rolling wheel to act on the bank or track-way solely by it’s weight; but this is not our only resource; for this wheel might be made of a moderate weight, and be pressed down by a brace reaching along the boat, toward the head and stern (see _k l_, fig. 3.), and _hauled taught_ through an eye of the socket _s_; by which _manœuvre_ (the points _k l_ being lower than the centre _A_ of the wheel) the latter will be pressed forcibly downward, and cause that cohesion there, from which the boat is ultimately to take her motion.

And, as to the wheel _A_ itself, I have _not_ represented it in the very form I should wish it to have, because it can be sufficiently described in words. I should cast this wheel (if made at all in metal) as a _shell_, the outside of which would be what is really seen in the figure (at _A_), and the rim would have in it mortices, like those which are made for iron wheels destined to receive wooden cogs, and geer with cogs of iron. In fact, this would become a wooden-toothed-wheel, with its teeth roughly formed and placed, so as to occasion a small expence, and to be easily changed, when worn away by the friction on the track-way. Thus would, I am persuaded, a very moderate weight in the wheel, and as moderate a pressure from the braces _k l_, connect the wheel with the road enough to produce the desired effect, with a trifling _loss_ of the power employed. And thus might we navigate a narrow canal, with a great saving of expence; not to mention that other advantage of avoiding entirely that injury to the banks, which must attend every system of propelling the boats, founded on the agitation of it’s waters.

OF A MACHINE, _For working, swiftly, the Slide-valves of Steam-engines_.

The Slide-valve is an excellent substitute for the _hand-geering_ of steam-engines, from the simplicity of form which it introduces, and the certainty of it’s recurring effects. But it is, I believe deservedly, reproached with being too sluggish in it’s operation, at the very moment when _activity_ would be most desirable--namely, at the beginning of the strokes; insomuch, say some, that the _power_ of the engine is materially lessened by it. The fact is, that the _excentric_ (usually placed on the crank-shaft) is almost always moving, and with it the slide-valves also; which thus open by _slow_ degrees, when they should open by _rapid_ ones.

Without discussing the question further, I cannot refrain from introducing this application of the principle of my Parallel Motion, given in page 237; which appears to me greatly calculated to obviate these difficulties; and thus to leave the slide-valve in possession of all it’s own advantages, with the addition of those which have hitherto belonged exclusively to the Hand-geering System.

I have represented this Mechanism in figs. 5 and 6, Plate 31: where _A B_ shew the crank-shaft of a steam-engine, working by means of slide-valves, the place of the _excentric_ being at _a b_, in a line with the pulling-bar _e f_. Instead, then, of the usual connecting _frame_ between the excentric at _a b_, and the valve-lever at _g_, I use for the above purpose, a lever _e f_ terminated by an arc _o_, furnished (in the present instance) with _five_ teeth, and connected by the joint _e_ with the valve-lever _g_, in the usual manner. In the arc, which terminates this lever _to the right_, are the five teeth above-mentioned; and, they geer in the _ten_ teeth of the wheel _c d_, which will be seen (in fig. 6) to be on the same shaft with the spur-wheel _m_, itself driven by the spur-wheel _n_, of twice the diameter. This wheel _c d_, therefore, makes two revolutions for one of the crank-shaft: and, supposing it to turn in the direction of the arrow, it will first of all draw _upward_ the arc _o_, producing no effect on the valve-lever at _g_; but, when the tooth _r_ is arrived at _p_ (the tooth _p_ being then arrived at the entrance of the curve _q_), the wheel _c d_ will begin to draw the arc _o_ along with it, round it’s own centre; and, the teeth of the arc being kept in it’s teeth by the similar curve _q_, the valve-bar will be drawn from _g_ to _h_, in the course of _one quarter_ of a revolution of the crank-shaft _A B_. But, now, the tooth _r_ of the arc _o_ will be found at _s_: and, therefore, the further revolution of the wheel _c d_ will carry the arc _o_ downward toward _t_, until the tooth _r_ has reached the point _t_; that is, until the wheel _c d_ has made another half-revolution, and the shaft _A B_ another quarter; when, as before, the arc _o_, conducted by the curve _t r_, will again drive back the lever _e f_, till it comes into it’s present position: after which, their motions will be regularly continued. It is, then, evident, that the slide-valves are thus opened and shut, each during one _quarter_ of a turn of the crank-shaft _A B_; and thus they remain stationary during another quarter, and that, in two positions of said shaft diametrically opposite to each other. And thus have we a simple mean, adaptable to every engine, of giving it much of the advantage of the hand-geering system, while preserving _all_ that of the slide-valve principle. And, were it desired to lengthen the _interregnum_ of the opening motion, it would be done by making the wheel _c d_ smaller, and the ratio of _n_ to _m_ (see fig. 6) larger in the same proportion.

I observe here, however, that care should be taken not to make the valve motions _too_ rapid, nor the intervals between them too long; for, I consider one of the best properties of this motion to be, that it acts _like an excentric_; that is, slowly at first, most rapidly afterwards, and finishes as slowly as it began; which is a _precious_ quality in all reciprocating machines.

Finally, I would remark, that the two last _rounds_ in the rack of the arc _o_ might be rather larger than the intermediate ones, and turn, moreover, on pins, so as to suffer less friction when rolling on the conducting curves _q_ and _t_. There might also be a plate or cap rivetted or screwed over all the teeth, so as to strengthen each one, by the force of the whole, as is shewn in fig. 1, Plate 29; from which, as before observed, this Mechanism is deduced.

* * * * *

The foregoing completes the Third Section of my work: and gives an article beyond the twenty, first intended:--which I thought important enough to claim this distinction. I now beg leave to add a remark or two on the text and plates of this, and the Second Part, by way of clearing up some obscurities, that might otherwise embarrass my readers.

And, first, in fig. 1, of Plate 21, the receiving vessel _M_, erroneously _appears_ to form part of the wheel _D E_; but is, in reality, placed _before_ it, as in all similar cases.--And, further, a small deviation of the circular lines, in Plate 22, has set the plate and it’s description, in page 192, _at variance_; the difference between the lines _o p_ and _C q_ being _not_ “imperceptible,” as there stated. I wish, then, that the dotted radius _A o p_, in the said fig. 2, may be carried (or supposed) halfway between _p_ and _C_. Finally, in page 200, line 8, the 24th Plate is incorrectly called the 25th.

I shall conclude this Part, by an observation or two on the reception my 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: