9. Mr. John Whitley Boswell has devised an apparatus which when attached to such a machine as that at Chemnitz will enable it to work itself without attendance. The description of this will be presented to the reader in Mr. Boswell's own words.

Fig. 3. pl. XVIII. A is the reservoir, or upper level of water. B, a chamber made of sufficient strength to bear the internal pressure of a column of water the height of A above it, multiplied by its own base.

c, a chamber of the same strength as B, but of a smaller size; it is placed at the bottom of the pit from which the water is to be raised, and under the level of the water.

These chambers would be stronger with the same materials, if of a globular or cylindrical form; but the square shape is used in the drawing merely for the facility of representing the position of the parts.

D, a pipe from the reservoir A which passes through the top of B, and ends near its bottom, to convey water from A to B. E, a pipe from the top of в to the top of c, to convey air from B to c.

F, a pipe from the bottom of c to the level of the ground at the top of the pit, to carry off the water from the pit.

it.

G, a pipe from the bottom of в to carry off the water from

H, a vessel to contain the water used in working the cocks; it is only placed on the top of: to save the construction of a stand on purpose for it.

1, a cock, or moveable valve (worked by the lever there represented), in the large pipe D.

to H.

K, a stop-cock in the small pipe which conveys water from D Its use is to make the engine work faster or slower, by letting water more or less quick into H; or to stop it altogether from working when required.

L, a moveable valve or cock in the small pipe LK. The lever which works it is connected by a strong wire with the lever which works 1, and is balanced by a weight at its opposite extremity, sufficient to open both these cocks and shut N, when not prevented by a counter weight.

N, a cock in the pipe G to open and shut it as wanted.

o, a self-moving valve in the pipe F, which permits the water to pass upwards, but prevents its return.

P, a self-moving valve at the bottom of c, which permits the water to pass into c, but prevents any from passing out of it; it is furnished with a grating, to prevent dirt getting in.

I

R, a vessel suspended from the levers of 1 and L, capable of containing a weight of water sufficient to shut them Q

VOL. II.

s, a vessel suspended from the lever of N: it must contain water enough by its weight to open N: it is connected by a chain to R, to keep it down as long as N is open.

T, a syphon passing from the bottom of H1, near its upper edge, and down again to the mouth of R.

v, a self-moving valve of a sufficient levity to rise, when the water in B comes up to it, and close the pipe ; into which no water would else pass from B. A ball-cock, such as used in common water cisterns, would do here.

x, a syphon from the bottom of R rising within an inch of its top, and passing down again to the mouth of s.

Y, a small pipe at the bottom of s: this may have a stopcock, to regulate it, which, when stopped, will also stop the engine.

The mode of this engine's working is as follows: suppose the vessels V, H, R, and s empty of water, and the cocks K and Y open, and the vessel c full of water. The weight on the lever of L will then open the cocks L and I, on which the water from A will flow into в and H. As the water rises in B, it will force the air through E into C, which strongly pressing on the water in c, will force it up through the pipe F, till the water in B rises to the lever of v and closes it, at which time н will be full of water (the quantity flowing in being so regulated by the cock к), and the water will flow from it through the syphon T into the vessel R, which as it fills shuts the cocks and L, and prevents any more water coming into B and H. When R is full, the water flows through its syphon x, which fills s, and by it opens N, which empties B of water, and keeps N open as long as there is any water in H.

When H is empty, в will be so too (being so regulated by the cock K), on which, in a moment or two, R and s will also be empty; which will cause the cocks 1 and L to open, and all things will be again in the state first supposed, for a repetition of the operations described.

To stop the engine, the cocks at K and y should be shut, while s is full of water. To set it working, they should be open; and this is all the attendance it will require. As no one but an engineer should attempt to construct such an engine as this, it was useless to represent the manner of connecting the pipes by flanches or otherwise; or the proper methods of fastening and closing the parts, which are all well known to such as have made this art their study. (Nicholson's Journal, 4to. vol. I.)

In No. 5. of the New Series of Nicholson's Journal, Mr. Boswell has made some further improvements in the application of the Hungarian machine.

10. The Spiral pump is a very curious hydraulic engine, which operates on nearly the same principle as the Hungarian machine. wben's The first engine of this kind, of which we have seen any account, Hydraulics was invented and erected by H. Andreas Wirtz, a tiuplate

worker of Zurich, at a dye-house in Limmat, in the vicinity of £363that city. It consists of a hollow cylinder, like a very large grindstone, turning on a horizontal axis, and partly plunged in a cistern of water. The axis is hollow at one end, and communicates with a vertical pipe. This cylinder or drum is formed into a spiral canal, by a plate coiled up within it like the main spring of a watch in its box; only the spires at a distance from each other, so as to form a conduit for the water of uniform width. This spiral partition is well joined to the two ends of the cylinder, and no water escapes between them. The outermost turn of the spiral begins to widen about of a circumference from the end, and this gradual enlargement continues nearly a semicircle, this part being called the horn: it then widens suddenly, forming a scoop or shovel. The cylinder is so supported that this shovel may, in the course of a rotation, dip several inches into the water. As the cylinder turns upon its axis, the scoop dips and takes up a certain quantity of water before it emerges again. This quantity is sufficient to fill the horn; and this again is nearly equal in capacity to the outermost uniform spiral round.

After the scoop is emerged, the water passes along the spiral by the motion of it round the axis, and drives the air before it into the rising pipe, where it escapes. In the mean time, air comes into the mouth of the scoop; and when the scoop again dips into the water, it again takes in some of that fluid. Thus there becomes a part filled with water, and a part filled with air. Continuing this motion, a second round of water will be received, and another of air. The water in any turn of the spiral will have its two ends on a level; and the air between the successive columns of water will be in its natural state; for since the passage into the rising pipe or main is open, there is nothing to force the water and air into any other position. But since the spires gradually diminish in their length, it is plain that the column of water will gradually occupy more and more of the circumference of each. At last it will occupy a complete turn of some spire that is near the centre; and when sent further in by the continuance of the motion, some of it will run back over the top of the succeeding spire. Thus it will run over into the right-hand side of the third spire; and consequently will push the water of this spire backwards, and raise its other end, so that it will likewise run over backwards before the next rotation be completed. At length this change of disposition

will reach the outermost spire, and some water will run over into the horn and scoop, and finally into the cistern.

But as soon as water gets into the rising pipe, and rises a little into it, it stops the escape of the air when the next scoop of water is taken in. Hence there are then two columus of water acting against each other by hydrostatic pressure, and the intervening column of air: they must compress the air between them, and the water and air columns will now be unequal: this will have a general tendency to keep the whole water back, and cause it to be higher on the left or rising side of each spire than on the right or descending side: the excess of height being just such as produces the compression of the air between that and the preceding column of water. This will go on increasing as the water mounts in the rising pipe; for the air next to the rising pipe is compressed at its inner end with the weight of the whole column in the main: and it must be as much compressed at its outer end, which must be done by the water column without it; and this column exerts this pressure partly by reason that its outer end is higher than its inner end, and partly by the transmission of the pressure on its outer end by air, which is similarly compressed from without. Thus it will happen that each column of water being higher at its outer than at its inner end, compresses the air on the water column beyond or within it, which transmits this pressure to the air beyond it, adding to it the pressure arising from its own want of level at the ends. Consequently, the greatest compression, viz. that of the air next the main, is produced by the sum of all the transmitted pressures; and these are the sum of all the differences between the elevations of the inner ends of the water columns above their outer ends: and the height to which the water will rise in the main will be just equal to this sum.

Suppose the left-hand spaces of each spire to be filled with water, and the right-hand spaces filled with air, as is shewn, in regard to one spire, in fig. 3. pl. XVII. There is a certain gradation of compression which will keep things in this position: for the spaces manifestly decrease in arithmetical progression ; and so do the hydrostatic heights and pressures: if, therefore, the air be dense in the same progression all will be in hydrostatical equilibrium. Now this may obviously be produced by the mere motion of the machine; for since the density and compression in each air columu is supposed inversely as the magnitude of the column, the quantity of air is the same in all; therefore the column first taken in will pass gradually inwards, and the increasing compression will cause it to occupy precisely the whole right-hand of every spire. The gradual diminution of the water columns will be produced, during the motion, by the water

running over backwards at the top from spire to spire, and ultimately coming out by the scoop. Since the hydrostatic height of each water column is now the greatest possible, viz. the diameter of the spire, it is evident that this disposition of the air and water will raise the water to the greatest height. This disposition may be obtained thus: let CB be a vertical radius of the wheel, c being the centre, and в the highest point [the figure may easily be drawn]; upon CB, take CL to CB, as the density of the external air to its density in the last column next the rising pipe or main; that is, make CL to CB as 34 feet (the height of the column of water which balances the pressure of the atmosphere), to the sum of 34 feet, and the height of the rising pipe: then divide BL into such a number of turns that the sum of their equal diameters shall be equal to the height of the main; lastly, bring a pipe straight from L to the centre c. Such is the construction of the spiral pump, as originally invented by Wirtz: it certainly indicates very considerable mechanical knowledge and sagacity.

But, when the main is very high, this construction will require either an enormous diameter of the drum, or many turns of a very narrow pipe. In such cases it will be much better to make the spiral in the form of a corkscrew, than of this flat form like a watch-spring. The pipe which forms the spiral may be wrapped round the frustum of a cone, whose greatest diameter is to the least (which is next to the rising pipe) in the proportion just assigned to CB and CL. By this construction the water will so stand in every round as to have its upper and lower surfaces tangents to the top and bottom of the spiral, and the water columns will occupy the whole ascending side of the machine, while the air occupies the descending side. This form is far preferable to the flat form: it will allow us to employ many turns of a large pipe, and therefore produce a great elevation of a large quantity of water.

The same thing will be still better accomplished by wrapping the pipe on a cylinder, and making it gradually tapering to the end, in such a manner that the contents of each spire may be the same as when it is wrapped round the cone. It will raise the water to a greater height (though certainly with an increase of the impelling power), by the same number of spires, because the vertical or pressing height of each column is greater.

In the preceding description of this machine, that construction has been chosen which made its principle and manner of working most evident, namely, that which contained the same material quantity of air in each turn of the spiral, more and more compressed as it approaches to the rising pipe. But this is not the best construction: for we see that in order to raise