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represented at C, D. It consists, simply, of an erect boredruns, or of a leaden cylinder, furnished with two opposite arms,lavung a valve at the bottom ; which is so constructed as to pre-sent the return of the water; and another valve at the extremity!!' each arm, for excluding the access of air above the current ofthe water, while the latter flows out. c, c, c, c, a circular troughjor the reception of the streams from C and D, to convey them tothose situations where the water may be required. We shall con-cede this article with a description of two famous water-works,trie one erected at Zurich , and the other at Florence. One of thegreatest curiosities of Zurich is the pump invented and erected byO. Andrew Wirtz, a tinplate-worker of that city. The inventionshews him to have been a man of very uncommon mechanicalknowledge and sagacity. It is a machine constructed to operate0,1 principles entirely different from those of all other hydraulicengines; and is very perfect in its kind. (Plate CLXIII. fig. 4.)exhibits a sketch of the section of this machine, as it was first erectedby Wirtz at a dye-house in Limmat, in the suburbs of Zurich . Itconsists of a hollow cylinder, like a very large grindstone, turningcn a horizontal axis, and partly plunged in a cistern of water.The axis is hollow at one end, and communicates with a perpen-dicular pipe CB Z, part of which is hid by the cylinder. ThisCylinder or drum is formed into a spiral canal by a plate coiled up J"'•thin it like tiie main spring of a watch in its box; only the spires jar e at a distance from each other, so as to form a conduit for the' v ater of uniform width. This spiral partition is well joined tothe two ends of the cylinder, and no water escapes between them.The outermost turn of tire spiral begins to widen about |ths of acircumference from the end, and this gradual enlargement con-tinues from Q to S nearly a semicircle: this part may be calledthe Horn. It then widens suddenly, forming a scoop or shovelSS. Th e cylinder is supported so as to dip several inches into thewater, whose surface is represented by VV. When this cylinder•s turned round its axis in the direction ABEO, as expressed bytile two darts, the scoop SS’dipsatV', and takes up a certain quan-tity of water before it emerges again at V. This quantity is suf-ficient to fill the taper part SQ, which tve have called the Horn ;and this is nearly equal in capacity to the outermost uniform spi-ral lound, Alter the scoop has emerged, the water passes alongthe spiral by the motion of it round the axis, and drives the airbefore it into the rising pipe, where it escapes. In the mean time,air comes in at the mouth of the scoop, and when the scoop againdips into the water, it again takes in some. Thus there is now apart filled with water, and a part filled with air. By continuingthis motion, we receive a second round of water, and another ofair. The water in any turn of the spiral will have its two ends on a jlevel ; and the air between the successive columns of water will behi its natural state; for since the passage irt the rising-pipe orMain is open, there is nothing to force the water and air into anyother position. But since the spires gradually diminish in theirlength, it is plain that the column of water will gradually occupymore and more of the circumference of each. At last it will oc-cupy a complete turn of some spiral that is near the centre; andwhen sent farther in, by (he continuance of the motion, some of itwill run back over the top of the succeeding spiral. Thus it willrun over at Iv4 into the right band side of the third spiral. Thereforeit will push the water of the spire backwards, and raise its otherend, so that it also will run over backwards before the next turnhe completed. And this change of disposition will at lastre ach the first or outermost spiral, and some water will run :" v er into the horn and scoop, and finally into the cistern.But as soon as water gets into the rising-pipe, and rises a little in!t > it stops the escape of the air when the next scoop of water ista ken in. Here are now two columns of water acting against eachother by hydrostatic pressure and the intervening column of air.

■* hey must compress the air between them, and the water and air-oolumns will now be unequal. This will have a general tendencyt0 keep the whole water back, and cause it to be higher on the left0r rising side of each spire than on the right descending side. TheOkcess of height will be just such as produces the compression ofme air between that and the preceding column of water. Thisgoon increasing as the water mounts in the rising-pipe; for■•e air next to the rising-pipe is compressed at its inner end withe weight of the whole column in the main. It must be as muchmpressed at its outer end. This must be done by the water- :vol. iv.— no. 215. ,

column without it; and this column exerts this pressure partly byreason that its outer end is higher than its inner end, and partly bythe transmission of the pressure on its outer end by air, which issimilarly compressed from without. And thus it will happen thateach column of water, being higher at its outer than at its innerend, compresses the air on the water-column beyond or within it,which transmits this pressure to the air beyond it, adding to it thepressure arising from its own want of level at the ends. There-fore the greatest compression, viz. that of the air next the main, isproduced by the sum of all the transmitted pressures; and theseare the sum of all the differences between the elevations of theinner ends of the water-columns above their outer ends; and tiieheight to which the water will rise in the main will be just equalto this sum. Draw the horizontal lines K'K 1, K'K. 2, &c. andwot, mn, mn, &c. Suppose the left hand spaces to be tilled withwater, and the right hand spaces to be filled with air. There is acertain gradation of compression which will keep things in this po-sion. The spaces evidently decrease in arithmetical progression;so do the hydrostatic heights and pressures of the water-columns.If therefore the air be dense in the same progression, all will be inhydrostatical equilibrium. Now this is evidently producible bythe mere motion of the machine; for since the density and com-pression in each air-column is supposed inversely as the bulk ofthe column, the absolute quantity of air is the same in all; therefore! the column first taken in will gradually pass inwards, and the in-creasing compression will cause it to occupy precisely the wholeright hand side of every spire. The gradual diminution of thewater-columns will he produced during the motion by the waterrunning over backwards at the top, from spire to spire, and at lastcoming out by the scoop. It is evident that this disposition of theair ami water will raise the water to the greatest height, becausethe hydrostatic height of each water-column is the greatest possi-ble, viz. the diameter of the spire. This disposition may be ob-tained in the following manner; Take CL or CB as the densityof the external air to its density in the last column next the rising-pipe or main ; that is, make CL to CB as 33 feet (the height ofthe column of water which balances the atmosphere,) to the sumof 33 feet and the height of the rising-pipe. Then divide BL intosuch a number of turns, that the sum of their diameters shall beequal to the height of the main, then bring a pipe straight fromL to the centre C. The reason of all this is very evident. Butwhen the main is very high, this construction will require a verygreat 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 formof a cork-screw, as in fig. 5, instead of this flat form like a watch-spring. The pipe which forms the spiral may be lapped roundthe frustum of a cone, whose greatest diameter is to the least(which is next to the rising pipe) in the same proportion that weassigned to CB and CL. By this construction the water will standin every round so as to have its upper and lower surfaces tangentsto the top and bottom of the spiral, and the water-columns willoccupy the whole ascending side of the machine, while the air oc-cupies the descending side. The following are dimensions of amachine erected at Florence, and whose performance correspondedextremely well with the theory, may serve as an example: The'spiral is formed on a cylinder of 10 feet diameter, and the diameterof the pipe is 6 inches. The smaller end of the horn is of the samediameter; and it occupies three-fourths of the circumference, andis 7 and 8-lOths inches wide at the outer end. Here it joins thescoop, which lifts as much water as fills the horn, which contains4340 Swedish cubic inches, each = 1,577 English , The machinemakes six turns in a minute, and raises 1354 pounds of water, or22 cubic feet, 10 feet high in a minute.

W AT FORD, a town of Hertfordshire , seven miles S. by W. ofSt. Alban’s, and 14 N. W. of London . Lon. 0. 17. W. Lat. 51.41. N.

WATLINGTON, a town of Oxfordshire , fourteen milesS. E. of Oxford, and 46 W. of London . Lon. 1. 0. W. Lat. 51.37. N.

WATTON, a town in Norfolk , eighteen miles S. W. of Nor-wich, and 90 N. N. E. of London . Lon. 0. 33. E. Lat. 52.36. N. ■ T

WATTS, Dr. Isaac, an eminent dissenting minister, born atSouthampton in 1674. In 1690 he was sent to London for edu-cation under the Rev. Thomas Rowe; and in 1696 was himself en-10 G gaged