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322

PICKWORTH'S PADDLE-WHEEL.

PICKWORTH'S PADDLE-WHEEL. The prefixed engravings represent a new paddle which has been invented by Mr. Henry Pickworth, of Sipson, in the county of Middlesex, and for which Letters Patent have been granted. The advantages claimed for the wheel are,that it does away entirely with concussion, and therewith the tremulous motion so much complained of in steamvessels-that it produces no tail-water, and causes, consequently, no drag on the vessel, or on the power of the engine that it may be placed so deep in the water that the propelling-paddles on both sides shall constantly be below the surface, even in the worst weather-that the paddles may be generally so arranged that every paddle upon ceasing to be for the time a propeller, shall present itself obliquely to the floating medium, even though the wheel should be wholly submerged-that it is not liable to be da maged or obstructed in its action by the sea striking against it, and needs, therefore, no protecting-case or paddle-box (saving thereby a great deal of very inconvenient top weight), the only substitute requisite, and that but occasionally, being a screen of canvass, or some other light material, to prevent the spray from the wheel being blown upon the deckin fine, that it is equally effective, or nearly so, under all circumstances.

Fig. 1 is a side view of a paddle wheel of this construction; in which, for clearness sake, one half the body of the wheel, and also some of its appendages, are omitted. Fig. 2 is an end view of the same wheel, with all the parts complete. The same letters of reference indicate the same parts in both figures.

In fig. 1 the wheel is supposed to be at rest, with all the paddles placed edgeways, or nearly so, to the stem and stern of the vessel. In fig. 2 the wheel is sup posed to be in motion, and the lower paddles advancing.

The body of the wheel HH is substantially similar to that of the common paddle-wheel, only that it is much narrower. The radial arms have circular holes pierced through them at their extreme ends, in which holes revolve transverse bars (with cranks GG at one end) which carry the larger paddle-frames II. These frames support parallelogramic paddles KK, each of which turns on an axis, which axis runs from end to end of

the paddle parallel to its side edges; not, however, in the centre of the side, but at a short distance therefrom, projecting a little beyond each end. This axis is also so put into the frame as to turn toward the vessel's side as it closes upon the frame, by which means a sea striking the wheel even on its broadside would, it is apprehended, produce little, if any effect. D is a hollow shaft, moveable in a collar, the bore of which hollow shaft is of such dimensions, that the main shaft A shall just be able to work within it without touching it. To the outer end of this hollow shaft, and as near to the side of the vessel as may be convenient, is fastened an eccentric E; and to the inner end (which is within the vessel) there is fixed a wheel B, similar to the steeringwheel in large vessels. C is a cog-wheel for palls to act on, so that the said hollow shaft D, and thereby the eccentric E, may be fixed or moved at will. On the eccentric E there revolves a wheel F called the frame-governor, of the same diameter as the body of the wheel, and pierced like it with circular holes, which take the necks of the cranks GG, shown without support in fig. 1, the framegovernor F being in that figure omitted to render the drawing more intelligible.

The smaller paddle-frames II are firmly fixed to the body of the wheel, quite independent of the eccentric motion, and may be considered as an optional addition to the wheel, which is complete without them. They carry paddles like those in the revolvingframes, excepting only in point of size. These frames have holes in their radial bars, and also in their paddles, so pierced that when the paddles are in the position of fig. 1, the holes in the bars and the holes in the paddles are in a direct line, so that one rod may be passed through bars and paddles collectively, and thus maintain them in their relative positions whenever this may be required. The paddles are so put into the frames, both revolving and fixed, that they shall turn. upon their axes, taking a general bearing or support from the frames when propelling, at which time they are at right angles with the side of the vessel-and when not propelling, having other bearings or points of rest also within the frames, which retain them at right angles with the frames, or nearly so.

The lines SS, fig. 2, represent the axes

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of the paddles in the frames when revolving as well as when fixed; both have the appearance of being continuous, but they are not so in reality, that appearance being produced by the axes being in two planes, each of which is viewed edgeways.

The lines TT, fig. 2, seen through and between the revolving-frames II, are the transverse bars of the fixed frames.

The open paddle-frames, fig. 2, have their paddles coincident with their axes SS, and are thus partly hidden by them and partly confounded with them; it not being possible to display the foreshorten

ing of the paddles on so small a scale as that to which we are restricted by the size of our pages.

In fig. 1 the wheel, as has been observed, is at rest; but a wheel of this construction never could, in point of fact, be as represented, unless the paddles of the fixed frames were secured in the manner previously described-for the broader sides of the paddles in the fixed frames yielding to the force of gravity, would close those on the right hand, which, however, would be opened the moment that the wheel was set in motion for fo

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PICKWORTH'S PADDLE-WHEEL.

ward movement, that is to say, in the direction of the arrow; the centrifugal force, the pressure against the air, and the pressure against the water, all combining to produce the above effect. To obtain this effect, however, the centrifugal force of a moderate velocity would be more than sufficient. The paddles have been placed in this imaginary arrangement here represented, in order that their relative positions with the frames might be

seen.

Suppose fig. 1 to be set in motion in the direction of the arrow. By inspection it will be seen, that the revolvingframes below the main shaft have the broader sides of their paddles in advance of the circular motion of the body of the wheel, and the revolving-frames above the main shaft have the broader sides of their paddles in the rear of the said motion; while the fixed frames, both above and below the main shaft, have the broader sides of their paddles in the rear of the said motion. The paddles in the frames, both revolving and fixed, are so arranged, that in opening they shall not be able to attain to a perfect right angle with the frames, in order that when active pressure exists, their sides may be exposed thereto unequally. It will now be evident, that the active water pressure on the broader and advancing side of the paddles in the revolving-frame while descending having a preponderance over the pressure on the narrower and rear side of it, must turn the paddle and close the frame. When, again, the frame has passed the lowest point of the wheel, and ascended so far as to have no power as a propeller, the active water pressure will be in the rear of the paddle, which thus pressed behind will instantly yield and open the frame, so as to let the water pass through, instead of arresting it and causing it to act as a drag on the speed. The fixed frames must, of course, from the arrangement of their paddles, remain open.

Suppose, further, that the motion of the wheel were continued, and that by a heavy sea, or from any other cause, the entire wheel were submerged, the paddles below the main shaft would continue effective as before, while all the paddles, both revolving and fixed, that are above the main shaft, having their broader sides in the rear of the said motion, would neither give nor receive resist

ance; the wheel, therefore, would continue as effective a propeller as before, as will be clearly perceived by reference to fig. 2.

When a vessel has head-way upon her, and it is desired to "stop her," let the motion of the main shaft be arrested, as in the case of the common paddle-wheel; the way of the vessel through the water will suffice to cause a pressure in the direction of the arrow, the revolving frames which are closed will open, and the fixed frames which are open will close and form a drag upon the vessel like the common paddle-wheel, but much more effective in proportion as the opposing paddles are deeper in the fluid; and this action, it will be seen, is entirely independent of the cecentric, or any thing connected therewith. If the motion of the main shaft be reversed, then back action will be produced also, after the manner of the common paddle-wheel.

From the peculiar construction of Mr. Pickworth's wheel, the whole support of the revolving-frames, as well as of the fixed ones, is thrown upon the body of the wheel. What is called the framegovernor F has inerely to retain the revolving-frames in their assigned position, whatever that may be. The consequence is, that there is no friction upon the eccentric E beyond what the mere weight of the wheel F would produce, so that one man stationed at the wheel B is enabled by means of it to turn the hollow shaft D, and with it the eccentric E, round the main shaft, and thus change the position of the point of support of the wheel F, and thereby the position of the revolving paddle-frames.

If there should ever be occasion to substitute sails for steam-power, an iron rod being run through the holes in the radial bars of the fixed frames, and through the paddles corresponding thereto, as before described, the wheel would present the exact appearance of fig. 1; and the paddles in the fixed frames being thus made immoveable, as regards their frames, would act as lee-boards.

In crowded rivers, and under other circumstances where great care is necessary, it is intended that a man shall be stationed at the steering-wheel B, who with his foot may command the palls acting on C, and, by turning the wheel B, augment or diminish the power of the paddles on his side of the vessel, without

PICKWORTH'S PADDLE-WHEEL.

interfering with the action of the main shaft. When the paddles are in full action, one-half turn of the steering-wheel B renders them entirely passive; and if this be effected on one wheel while that on the other side remains in full force, the vessel is brought short round upon her heel, independent of the rudder, which may, however, be used at the same time.

From the water-line in the drawing, it will be seen that it is intended to place this wheel so deep in the water that no alteration in the loading or the trim of a vessel can sensibly affect its propelling power; in fact, unless a vessel be thrown nearly on her beam-ends, such a wheel as this can never be entirely out of water. Should the revolving-paddles ever become from any cause unmanageable, the fixed paddle-frames may be closed, and the paddles secured in that position by passing the rod, before spoken of, through the fixed frame radial bars merely; the wheel may be thus converted in a few minutes into the common paddle-wheel.

The fixed frames are so secured to the body of the wheel, that they may with their paddles be entirely removed in a few minutes without interfering with any other part of the machine; they may be replaced also in an equally short space of time. And when the fixed frames are so removed, the wheel will remain as effective as before.

Nearly the same effects may be produced in a different manner. Suppose the forward movement of the vessel to be effected as previously described, and that the command is given to 66 stop her." The stopping of the main shaft would merely arrest the propulsive power of the wheel, which in many cases is all that is desired; but should it be wished to add a drag upon the vessel's way, this may be regulated to any extent-from a mere line to the entire superficies of the whole of the immersed paddles-by a half-turn of the steering-wheel B, or so much less than a half-turn, as may be deemed suffi. cient. A reverse motion of the main shaft then gives the back action.

In order to protect the wheel from gunshots, it is intended that wheels on the principle of this patent shall be wholly submerged when applied to vessels of

war.

The arrangement shown in figs. 1 and 2, without the fixed frames and their paddles, would he suitable for such a

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purpose; but it will probably be found, in most cases, necessary to reduce the diameter of wheels so used, and to increase the number of their revolutions proportionately.

Following out this idea, let us suppose that the fixed frames with their paddles are removed, and that the highest paddle remaining is completely under waterthe wheel propelling in the direction of the arrow. Now, a half-turn of the steering-wheel B would, without reverssing or in any way interfering with the motion of the main shaft, instantly give back action equal to the fore action on the other side of the vessel; so that this movement of the steering-wheel B being performed on one of the two wheels only, the effect would be to bring the vessel round upon a point within her keel, and to make her turn gradually round upon that point as long as the wheels in that position could be impelled. A man-ofwar would thus have the advantage of being able to bring her broadsides to bear in succession upon any given point by a regular movement, without any effort beyond the first adjustment of the wheelsthe whole not the work of one minute.

The wheels in the case last supposed are assumed to be not only submerged, but in a vertical position like that of the common paddle-wheel. Mr. Pickworth, however, considers that his wheel would be quite as effectual a propeller, if attached to a vessel in a horizontal position, as in any other. All that is thought to be necessary is a modification in the arrangements of the vessel. A great breadth of beam, with a light draught of water, are the obvious requisites for a vessel with horizontal wheels; and these, it is presumed, might be combined with advantage for passenger-vessels and for war purposes. A vessel of the form somewhat like that displayed in the engravings, figs. 3 and 4, might perhaps be found suitable.

Fig. 3 is a side view, and fig. 4 bottom view. A, the gun or passenger deck; B, main-floor of the boat; C, the keelfloor; D, engine-room; E, wheels; F, rudder; G, the position which the wheel E would occupy if placed vertically in the usual manner; HH, coalholes; and I, line of floatation. Any modification of this arrangement which may suggest itself to the scientific builder might be very readily introduced. For

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BRIGHTON RAILWAY BILL.

example, the wheel itself may be made buoyant by a drum on the main shaft, if such an adjustment should be thought desirable.

We are inclined, on an impartial consideration of the whole subject, to think that Mr. Pickworth has rather attempted too much by striving to combine all the advantages of the best form of moveable float-boards with all the advantages of the common paddle-wheel; while, at the same time, to avoid the disadvantages of both one and the other, he has given a degree of weight to his wheel which may weigh considerably against it. It is, however, but justice to remark, that by a judicious arrangement of his materials he gets the needful strength with perhaps as little weight as possible. He will, we

hope, excuse us for suggesting, that his paddle-frame vertical bars might instead of plates of metal have rods (following the outline of the plates) substituted for them with advantage. In the case of a sea striking the wheel on its broadside, the rods would offer less resistance than the plates.

We beg these remarks to be understood as applying to figs. 1 and 2 only, for upon the horizontal wheel we do not venture to give an opinion; all that we can say is, the arrangement seems to us to be ingenious and worthy of consideration.

We are informed that it is the intention of Mr. Pickworth to charge no patentee's premium upon his wheels, but to give permission to all respectable engineers to manufacture them, on condition of his being paid a small annual charge upon every vessel to which they may be applied, so long as she may continue to use them. This, at all events, is a proof that no advantage is desired by the ingenious inventor other than what the real and positive superiority of his wheel may procure for him.

BRIGHTON RAILWAY BILL.

The Evidence against Tunnels. Sir Anthony Carlisle, M.D., examined by Mr. Hill.

I am vice-president of the College of Surgeons, and have been a public practitioner about forty-four years in London. As a part of my professional duty, but more especially in my scientific pursuits, I have attended to the subject of tunnels on railways. It must

necessarily happen that at very few seasons of the year there can be the same temperature in the external atmosphere and the stationary air in the body of the tunnel; there must necessarily be some marked difference, for in the winter season the air in the tunnel will be considerably warmer, and in the summer season the air in the tunnel will necessarily be colder than the external air. Such a variation of temperature will expose persons in health to the common affection notoriously termed catching cold, the source of other disorders; they may be inflammatory or they may be of other kinds; but the common phrase of catching cold, I believe, arises from its being found by experience that people are apt to take a disorder called a cold or catarrh by sudden transitions from heat to cold or from cold to heat. I entertain no doubt that the variations in temperature to which I have referred will be sufficient to put persons even in health in danger of cold by passing through a tunnel. I think it must of necessity be." so; for although a person may pass sometimes with impunity, he cannot be always assured of passing through a tunnel under the stated circumstances with impunity. Most striking effects would be produced on persons of weak constitutions or who are invalids. If your lordships and the Committee will permit me, I will generally state, without being too prolix, the reasons for my entertaining this opinion. The surface of the body and the inner surface of the lungs are the two portions of the living frame most exposed to the vicissitudes of temperature in the air. Persons with weak lungs being subjected to the alternation of heat and cold or cold and heat, by such transitions must necessarily have disordered conditions of the lungs aggravated; so in the influences upon the external surface of the body, catching cold is commonly and justly imputed to the external application of change of temperature; hence persons are said to "catch their death of cold in damp sheets," and on exposure to a current of air, because the current of air, though of the same temperature, does not accord with the temperature or halo immediately surrounding the living body, which in a healthy man is at 100 degrees, such halo surrounding his body approaching nearer to the temperature of his body than to the external atmosphere; and hence, if a stream of air blows upon him, it produces a sensation of cold, and in fact it has the effect of a different temperature from that which envelopes or surrounds the person. Besides catching cold in passing through a tunnel, a person is subjected to all the modifications of disorder of the lungs which have a tendency to inflammatory nature, active or chronic; and also erysipelas, a very dangerous disease, is known very frequently to hap

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