The second stamper c d fig. 3, whose place is at A fig. 2, is quite plain on it’s face; being destined merely to keep the metal to it’s thickness—as the particular nail here intended, is a floor nail, requiring a head on two sides only. As to the figured stamper b a, fig. 3, it meets a similar form in the anvil, as at e: and it is by the pressure of these half matrices, that the head is formed and the bar separated from the nail. It may be noticed that the stampers a b, c d, are shewn in the figures, as perfectly straight on the face: but the kind of motion resulting from that of the cranks, would require a gentle curve here, which a first experiment will sufficiently indicate.

Some skill would doubtless be necessary in presenting the nail bar to this Machine; but to make this operation the easier, there should be a guage, moving toward the working point e, by a given quantity for each nail: say that this guage comes forward at each time a distance equal to half the length of a nail; and that the thickness of the nail bar is so proportioned as to contain in that length, enough of metal for the nail when finished.

It remains to be observed, that the stampers or bars A, B, fig. 2, are contained, in the direction of their width; by two plates like f, connected with the anvil e, and leaving near e, an opening large enough for the nail-bar to pass easily.

OF
A MECHANICAL ASSISTANT
For the Tea Table.

This new method of tea-making admits the use of the common tea urn—which is placed on the table near the left hand of the fair distributor. This arrangement is given at figs. 4 and 5 of Plate 27. There, A is the Urn; and B any common tea-pot, for whose spout, the cock a, has been substituted; and the handle of which has been slightly modified, so as to make it a proper centre of rotation. This tea-pot is, of course, opened before it is brought into the position shewn in the figures. At C b c, is placed, first of all, on the table, a stand of metal, terminated upward by the stem C D which forms a vertical centre to the whole apparatus: and which is sufficiently fixed to the table by standing on three feet, b c, &c.; under which are stretched small pieces of Caoutchouc (or India rubber), which, by their adherence to the table, make the whole steady. By these means, the tea-pot can be turned round, by a gentle effort, till it comes under the cock of the urn, from which it receives the boiling water. And, finally, the tea-board, which is itself circular, revolves on the same axle C D, supported by the casters or rollers e f, and bringing successively all the tea-cups m, n, o, &c., to the spout of the tea-pot, where they are filled without the smallest difficulty, as will appear by a further inspection of the figures, and especially by an appeal to experience.

The above, I should presume, is all that need be said upon the subject. It remains for some rationally zealous friend of this social repast, to put these (or other analogous) ideas in practice: in which enterprize, should he succeed in pleasing the ladies, he may depend on the approbation of every lord who deserves the name.

OF
A COPPER-PLATE PRESS,
With curious and useful Properties.

This Machine, as intimated in the Synopsis, was invented expressly for the use of the lithographic art, as an improvement on the roller press used in Paris when that process was first introduced there. I have, however, seen in England the description of a Machine which takes the desired impression without any rolling motion. This Machine, in that description, carries a kind of scraper, or, as the calico printers would say, a Doctor, which, pressing on a line only (while drawn over the paper, or the paper under it), acts successively on every part of the sheet, and, no doubt, gives a good impression. Of the relative perfection of these methods, I do not presume to judge, as it is a technical question; and both Systems are, or have been, used. But, when intense pressure, joined to much precision, and great economy of power, are desirable, this Invention appears to me superior to any thing I have seen used for these purposes.

In fig. 1 and 2, (see Plate 28), A B are two horizontal planes of hard wood or metal, connected, at a proper distance, by the pillars C D, shewn in fig. 1 only. E F are two Sectors of a large cylinder, united at the point a, either by a good hinge or by a joint composed of a hollow prism fixed to the upper sector E, and of a solid one, more acute, fixed to the lower sector F; so that, in the latter case, this joint works with an insensible degree of friction, and thus occasions a great saving of power.

In the working of this Press, the joint just mentioned, however made, describes a straight line, parallel both to the floor B G and the ceiling H A, which have been already shewn to be parallel to each other: and thus are the joint a and the sectors E F suspended to the cap or ceiling A H by a pair of triangular braces I a K, which slide smoothly in two dove-tailed grooves A m. Moreover, to the lower sector F are fixed two working arcs b c, one on each side of the Press, and whose radii are exactly equal to that of the upper sector E (whose circumference, therefore, is invisible in fig. 1.) Further, just above these arcs, and in the middle of the slide I K, are placed, on proper centres, a pair of grooved pulleys P, destined to work the under sector, without disturbing the motion of the upper one, which latter is a rolling motion under the aforesaid ceiling A H. For the said purpose, a metallic cord or chain is fixed at m (fig. 1), which, passing round one of the pulleys P, is led to the end n of the arc b c, n o; and near A is fixed a similar cord, which, carried round the other pulley at P, is led to the angle o of the same arc b c, n o. By these means, the sector F is fixed both in place and position, as long as the slide I K retains it’s present position and state. But, again, a system of similar cords, placed under the ceiling A H, near the edges of the upper sector E, determines the place of that sector, in every case, except a change of position; for a rolling motion can still have place, without occasioning any other change.

When, therefore, a pulling bar, a crank and fly, or any other prime mover, applied at the joint a, carries that joint (say) toward the pillar D, that motion takes place without any rubbing of surface either above or below; for, when the upper section has rolled under the ceiling A H, into the position n p q, the lower section has rolled upon the plate s t, into the position q r s: in such sort that the analogous angles o t, p r of both sectors are always found in the same perpendicular line—or plane—o t, p r; the cause of which I shall now endeavour to unfold.

When a wheel, in general, rolls on or against any fixed plane (and the cords m P, A P, now act the part of a fixed plane), the point of it’s circumference the most distant from that plane, moves, in a direction parallel to it, just twice as fast as the centre of such wheel, because it is twice as far from that plane, the virtual centre of its motion: (an example of which is found in the wheel of a carriage, whose top moves forward just twice as fast as it’s axle-tree.) Supposing, then, in the present case, the frame I a K, with the pulleys P to glide toward the right hand, the cord A o fixed near A, will turn the arc b c to the right, twice as fast as the centre of the pulley P moves in that direction: and if this impulse had acted on the joint a, while fixed in position, the arc b c would have turned too much by half. But it so happens (if this expression may be used), that the joint a itself moves in that direction once as fast as the pulley-pin; so, that the motion remaining to the sector F is a single motion, merely sufficient to keep the two sectors E and F directly under each other, or within the same perpendicular lines p r, n q s, &c.

Thus, it appears, that the turning motion of the two sectors is the same; and that a given point of the lower one will always visit the same point of the corresponding plane s t, independently of contact with any substance lying on it; and that, therefore, the pressure, though successive, is perpendicular, having no tendency to displace or pucker the paper laid on it; besides which, it may be observed, that the power of this Press is immense, from the length of the radii of the sectors E F, and the absence of any rubbing motion.

I observe, further, that racks, made with teeth on my principle, either singly inclined with cheeks, as in Plate 14, or with teeth in the V form, will produce a more certain effect than the cords and pulleys above described, provided the arcs b c, and the upper sector E, be prepared and toothed accordingly.

OF
A REFLECTOR
For Lighthouses, &c.

From the nature of reflecting curves, it follows that the smaller a luminous point is, the more perfectly will its emanations be reflected; for a focus is a point of the smallest magnitude, if, indeed, it has any dimensions. My idea, then, is to make a focus of a line of light very minute in it’s section, but as large, in it’s contents, as may be desired: thus securing a considerable fasces of luminous particles while using them in an economical manner. To this end (see Plate 28, figs. 3 and 4), I form my reflecting surface of two distinct parts, having a section common to both, viz.—1st. a concave-parabolic-spindle, represented at A B C, as cut by a vertical plane passing through it’s centre; and 2ndly, a parabolical bason E D F G (represented in the same manner) surrounding the former, and so placed as that these surfaces have a common focus—namely, the circular line of which a b is the section; the line itself being shewn by an elevation passing behind the aforesaid spindle A B C. This linear focus, therefore, may be two or three feet in diameter; thus imitating the tenuity of a punctual focus, while emitting a large quantity of rays.

This Lamp, then, consists of an oil vessel, which is formed by the outside of the parabolical bowl before-mentioned, surrounded, in it’s turn, by the cylindrical surface P H, I Q, this vessel communicating with the wick-ring a N, b O, by a passage, H I, made as thin as possible, in order to leave the light at greater liberty to pass downward after reflection. (Where it is proper to add that the wick-ring is drawn too thick in the figure.) Now, it is well known that all rays of light issuing from a point, and falling on the concave surface of paraboloid belonging to that point as a focus, are reflected from it in lines parallel to each other; and, therefore, a great part of the particles emanating from the linear (or circular) focus a b, and impinging on the surfaces F G A B, and B C D E, will be reflected perpendicularly downward, as at a, 1 3; b, 2 4, &c. and this being the case all round the common centre B, there will be formed a cylinder of light of the diameter H I, diminished only by the shadows of the wick-ring, the passage H N O I, and the pillar B L, when that is used, which is not indispensable.

If this cylinder of light strikes on the plane mirror K H, placed at an angle of 45° from their direction, these rays will be reflected horizontally, and, preserving their cylindrical form, may serve as a powerful beacon to the benighted mariner; the more useful, because susceptible of those temporary variations of direction and aspect, long since employed to distinguish one station from another.

But, if it were desired to illuminate a large space at sea, or elsewhere, the aforesaid cylinder of rays would be received on a conical surface K L M, which would give it the form of an immense sheet of light, of a thickness (allowing for aberration) equal to the height of P L M, of the same conical surface.

I shall add only one idea—namely, that to light any round space, building, theatre, &c., this system might be made very efficient by throwing the sheet of light M P higher or lower on the walls, &c.; or (altering the angle of the cone K L M) by bringing it down to any position in or below the horizon, as circumstances may direct.

It would be superfluous to say that this Lamp might be furnished with all the advantages of the argand principle; or, the whole wick-apparatus might be superseded by a circle of minute, and very numerous gas lights, forming, sensibly, the same linear focus; or a thin circular slit might produce a real ring of light, strengthened by all the resources of this new and splendid discovery.

OF
A LONG PARALLEL MOTION,
For Mangles, and other Reciprocating Machines.

In the year 1793 or 4, I received a written problem, desiring me to give a plan of a long Reciprocating Motion, that should be driven by the pit-wheel of a common water-wheel, of given dimensions, and placed in a given position. In a few days, I produced the drawing now represented in Plate 29. Its object, as required, was to move the cylinders L M, figs. 1, 2, 3, backwards and forwards, in the long grooves or gutters N O, for the purpose of crushing or bruising their contents: but what those contents were I never knew. I, however, produced this Machine, considering it as a general thing, and of a nature to perform most operations of a similar kind. The Machine consists—first, of a long rack I K, much like a narrow ladder placed on it’s edge, and in the teeth of which work those of a pinion p, whose axis q is connected with the wheel r, which receives it’s motion from the vertical wheel s t, which is the pit-wheel in question. This communication takes place by means of an universal joint x, being a mean of permitting the pinion p to vibrate from side to side of the rack I K, when arrived at either end of it. For example, the pinion p now turns from left to right, and, being on the other side of the rack, and held by the chain v, it drives the slide P Q in the same right-handed direction, and, with the slide, the two heavy cylinders L M before-mentioned;—for, the said slide P Q carries across it’s middle the axle-tree S T, which is the centre of both these cylinders, and connects their motion with that of the slide now in question. Further, there are rollers placed between the cheeks V V, on which the slide moves horizontally, as guided by other rollers, placed at the points 1, 2, 3, 4, &c. Again, the ends of the axle-tree S T are furnished with two bow-like bridles, which, connected with the pulling bars Y, are again fastened to the slide P Q, at the two ends of the present figure.

When, now, the pinion p turns (see fig. 1 and 3), the rack, slide, and cylinders roll in the grooves, till the end of the rack comes to that pinion; which, finding no more teeth, swings round the last, and taking a new position, reverts the motion, till the other end of the rack comes to it, and occasions another return: ad inf. This will be better seen at the third figure, which is an end elevation of a part of the Machine.—There, P shews the slide and one of the teeth of the rack (which teeth are longer than the rest, as seen near L M, in fig. 1.) In this figure, we see at A, a mass of brick-work, covered by the sleepers 5, 6, 7, &c., on which the long cheeks V V repose. There, also, the chains v z are seen, connected with ring-bolts, which go through the bars a b, and are nutted on the other side of the spring-beams c d, in order to avoid the commotion which would otherwise attend every change of motion in the slide and cylinders. For this purpose, also, and especially to prevent any waste of power at these moments, there are mixti-linear wedges laid in the gutters, such as are shewn at 6, which are formed so as to absorb the momentum of the cylinders, in exact conformity to the time employed by the pinion p, in swinging round the end tooth of the rack; and thus to save all the power and time possible.

OF
A MECHANICAL SYPHON:
Which expels Part of it’s Water at the upper Level.

An ordinary Syphon acts by the pressure of the air on the upper water, which drives it into the ascending pipe, because there is a (partial) vacuum made there by the weight of the falling water in the descending pipe; this being always longer than the first. Thus, in Plate 29, fig. 5, A B shews the rising pipe of a Syphon, and C D the falling pipe, which is longer, and sinks to a lower level D, than that A of the water, which feeds the machine. E, in this figure, represents the vessel containing the mechanism on which the new effect depends: and which I shall now describe.

B and C, fig. 4, are, one the ascending pipe A B of fig. 5, and the other the descending pipe C D. They are surmounted by two cylinders, of unequal capacities—this inequality bearing a given proportion to the difference in the heights of the rising and falling branches of the Syphon. In each of the cylinders works a piston a, b, which, I think, need not be stuffed, but well fitted. The large piston has proper valves in it, to let the water pass upwards, at all times; and the small piston has a valve i, opening upwards, by means of the mechanism we are now describing; and closing itself merely by the arrival of the piston into it’s present position; for the screw c prevents the valve from rising higher: e, f, are two arcs belonging to the lever E, and being circles round it’s centre of motion. They are cut into teeth, on my Patent principle, and work in the racks similarly toothed, which give motion to the pistons a b, or receive it from them. Further, behind the stand F, common to both levers, vibrates, on a pin, another lever g h, the use of which is to work the aforesaid valve i in the small piston; and this it does, by means of the weight h, in the following manner:—The machine being supposed in the present state, the Syphon will act, as usual, through the valves of the large piston; and the water pressing on the small one, with a power proportionate to the excess of it’s column over that of the other piston (a), will raise the latter as fast as the piston b descends; but the area of the piston a being larger than that of the piston b, there will be a pressure within the vessel b c d a, that must expel (through any prepared aperture at the top) a quantity of water equal to the difference of area between the two pistons, multiplied by the stroke of both: the real quantity of which will ultimately depend on the difference of level between the higher and lower water; or between the lengths of the rising and falling branches of the Syphon, B and C. When, therefore, this stroke is made, the end h of the lever g h, which carries the ball, will touch the screw d, and stop the descent of the valve i, which will thus be opened; when the water will have free egress through the descending pipe C, and the piston b will then rise through that water by the weight of the piston a, the valve i being kept open by the action of the weight h, until the piston b has risen to it’s present position, when a new stroke is prepared, for the same reason as before: and thus may water be carried over a hill of (about) 30 feet above the level of any stream or pond, and dropped into a lower canal on the other side, with the condition of leaving a part of that water upon the hill, proportionate to the difference between the level from which the water is brought, and that to which it is carried.

OF
A FORCING MACHINE,
For taking on and off the Cylinders of Calico Printers.

The two figures, 1 and 2, of Plate 30, are intended to make this Machine known, assisted by the following description:—The first is a front view of it, and the other a partial view from above. In the former, A B is the frame formed of, and firmly connected with the two columns C D, which are fixed strongly to the ground, at such a distance below the ends C D, as to place the aforesaid frame at the height of about two feet, or higher, if convenient.

In the two cheeks of the frame A B, are cast or bored two round holes for receiving the gudgeons of the swivel E, one of which gudgeons is also seen at E, in fig. 2. This swivel turns in these holes; and it is itself perforated with a round hole just large enough to receive freely the body of the mandrel F G. This mandrel has now on it the cylinder, which is to be taken off. I K are, moreover, two ears or studs cast or welded on to the top and bottom of the said frame A B, and at exactly the same distance from the centres of the swivel E before-mentioned. These ears receive the ring-formed ends of the bars L M; see also the bar L, in fig. 2. To these bars is firmly fixed the cross-bar N O, which forms the nut of the screw P, by means of which the operation of the machine is duly prepared; for, now the cup Q (in the centre of which the screw P revolves against a proper shoulder) receives the end G of the mandrel, which it presses forcibly, while the whole is in the position E L, of fig. 2; that is, when the two centres E and R form one right line with the bar L, figs. 1 and 2. To complete, then, the process of driving out the mandrel, the bars, mandrel and cylinder are, at once, strongly made to describe the arcs a M b, a c; the mandrel revolving round the centre E, which is that of the swivel and the bars round the stud R. But, in thus revolving, a given point of the mandrel describes the quadrant a M B, and a contiguous point of the bars L M describes the quadrant a c; insomuch, that the mandrel must have been forced out of the cylinder in direction G F by the distance c b; where we observe that, at the beginning of this motion, the two curves a b and a c coincide in their movements, and only begin greatly to diverge from each other in the latter parts of these motions (see M b c.) The power, then, of this machine, when the cylinder sticks fastest to the mandrel, is infinite: and this power becomes weaker, and the velocity greater toward the end of the operation; that is, when the cylinder has slackened on the mandrel, and no longer requires to be driven with the same force as at the beginning. It may finally be observed, that the bars L M are suspended by an oblique bar or chain S N to the ceiling of the room just over the stud R or I, which is their real centre of motion, in the above-described process.

OF
A SYSTEM OF MACHINERY,
For cutting and trying Tallow by Power.

The wheel A B, Plate 30, fig. 3, was a horse-wheel, but may be a first motion of any given kind. It is placed on the ground-floor; and over it’s centre is another shaft, having on it’s upper end a chopping block C, which revolves with the wheel A B, as turned from below. In this wheel, A B geers a pinion D, driving the lateral shaft D E, which has two functions: the first to work the lying shaft F, and by means of the cams G H, to lift the contiguous stampers; and, by means of the knives I K, to cut the tallow on the revolving block before-mentioned. Over this block is fixed an oblique scraper, which takes the tallow as soon as it is cut, and pushes it down an inclined channel, placed at C x, into the boiler. The second use of the shaft E is to turn the mill M, (better shewn at fig. 4), which is let down into the boiler, in one stage of the process, and drawn out by the tackle N, when not wanted. The use of this mill is to tear the fleshy parts of the substance, while in the act of boiling, and thus to disengage the tallow with so much the less heat, in order that it may be so much the less coloured. Besides this machine, there is a grapple L to be first used, which stirs the tallow in the boiler by the rotatory motion of the arm x. This position of the grapple would alone indicate what I have yet to observe—namely, that the boiler is a kind of ring, the section of which is the line 1, 2, 3, 4, and it’s depth 1, 2, or 3, 4. To prevent, still further, the fat from being burnt or coloured, the flue for the fire is conducted solely under the bottom of the boiler, as shewn by the dotted lines in fig. 5: the smoke or heated air being forced to make two revolutions under it, as indicated by the arrows in this figure, where we see more particularly the fire-place F in close connection with the rising shaft of the chimney at G; and this is so, because, with so great a length of horizontal flue, the fire would not enter the chimney till it had been heated to a first degree. There is, therefore, an opening into the chimney at a, and the fire, in lighting, is suffered to escape directly from the fire-place into the chimney; by which means, continued a few minutes, there is draught enough created to make the fire take its useful course through the flue afore-mentioned. I may just observe, reverting to fig. 3, that O shews the fire-place in elevation, and p the entrance into the flue, which last is double under the boiler, as shewn in fig. 5. Finally, the 4th fig. shews an end view of the tearing-mill, before-mentioned; but here on a larger scale, A B being a part of the side of the boiler.

OF
A WASHING MACHINE, FOR HOSPITALS,
Which confines the offensive Matter till cleansed away.

Doubtless, the salubrity of every place, where many people are collected, would be much increased, if all impure exhalations were expelled as soon as formed; and this is especially true of those awful but sublime receptacles, provided by Philanthropy, for the sick, the wounded, and the dying! To assist in the work of purifying the atmosphere of these doleful abodes, was the object (30 years ago) of the Ventilator, presented in page 170 of this work. But, I conceive, that a share of evil, quite as great, resides in the putrescent qualities contained in or connected with the clothes, the bed-linen, the dressings, &c., of the inmates of an hospital; to whose sacred claims on the efforts of every good citizen, the present article is devoted.

This Washing Machine (see Plate 31, figs. 1 and 2) is a triangular (or square) box A B, furnished with a lid a b, so fitted, as, when screwed down, to be hermetically closed.—And, N. B., to facilitate this operation, I use in it a particular kind of screw (invented for the hose of fire-engines), which I shall now describe. I take a common screw, with it’s nut, and cut away the threads of both, at two opposite quarters of their respective circumferences, so that the screw can enter the nut to the bottom without turning; and the stuffing between the shoulders is so well fitted, in thickness, as to secure the penetration of the threads of the nut and screw the moment the latter begins to turn. There is thus a full quarter of a turn, in which the nut and screw will press as strongly as though the threads had not been cut away; and thus are nine tenths of the time required to use a common screw saved by this simple process: and thus, then, I close the lid afore-mentioned.

This Machine is further composed of a wheel C D, and a pinion E, to turn it with, either by hand, or by any proper application of power. The wheel turns the box A B, and thus agitates the contents in a way not dissimilar to the operation of the dash-wheels of calico printers. But, again, this wheel and vessel turn upon two hollow gudgeons c d; one of which is destined to convey cold water into the wheel from the reservoir F G, to regulate which is the use of the cock f: the stuffing box e being made as good as possible, in order to prevent all leakage, either of air or water. The second hollow axis d serves two purposes: it gives a passage to the fetid matter of which the expulsion is desired, and conveys it through the cock g to the sink or sough below h, without any communication with the surrounding atmosphere.

But we said this hollow gudgeon had a second use: it is to bring steam into the revolving vessel A B, from any proper boiler beyond K, when that part of the process requires it.—There are, moreover, two partitions C D, l m, made near the ends of the vessel, and pierced with many holes, in order to suffer the cold water to flow in, and the dirty water to escape, without choking up the respective passages: and, finally, at the eduction end of the Machine (see n, o, p, fig. 2), there are placed three pipes, reaching from the angles of the box to the hollow centre, and furnished, at those angles, with valves, opening outwards; which thus form a kind of hydraulic machine to raise this matter from those places to the hollow centre, and thus, after a certain number of revolutions, to expel it entirely.

The process, then, for cleansing the objects contained in the vessel A B (including the condition of cutting off all communication with the ambient space,) is as follows:—

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 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.