WATER. 



and there remain but few to be confidered in the prefent 

 article ; viz. the varieties of the hydrauhc ram, of the 

 Chremnhz fountain, and of the fyphon machines. 



The moil obvious means of raifing water is by the operation 

 called baling, that is, hfting up water-in a bucket, or other 

 veflel, by the force of a man's arm. This method is ex- 

 tremely fatiguing, and is only adapted to very fmall eleva- 

 tions, fuch as clearing the water from a boat, &c. The moft 

 ancient hydraulic machine afts on this principle, fuch as the 

 fcoop and troughs, the Fen wheel, Perfian wheel, the Noira, 

 &c. : it is, therefore, with tliefe machines we Ihall com- 

 mence. 



The Dutch luater-fceop, or fliovel, is the beft means of 

 baling out water. The fcoop is a kind of box, made of 

 live pieces of board, with one end and one fide open : this 

 box is fixed at the extremity of a long pole, which the 

 workman holds in his hand, and the weight of the fcoop 

 is borne by a cord tied to the pole near to the box, and 

 fufpended from a tripod, formed of three poles tied together 

 at the top. The man works the machine by fwinging the 

 fcoop backwards and forwards in the direftion of the length 

 of the pole ; in moving the box forwards, he depreffes the 

 end of the pole, which caufes the box to dip into the water, 

 and take up a quantity which it will throw forwards and 

 rather upwards to a confiderable diftance. In bringing the 

 fcoop back for another ftroke, he depreffes the end of the 

 pole which he holds in his hand, and thus keeps the box 

 out of the water. Of courfe this method is only appUcable 

 where the height to which the water is to be raifed, or rather 

 thrown, is very fmall. M. Behdor informs us, that a work- 

 man can only remove half a cubic foot in two vibrations, 

 which he will perform in four feconds ; this is at the rate 

 of 7| cubic feet per minute, or 450 cubic feet per hour : it 

 is rareJy apphcable, except to throw the water over a bank 

 which forms the boundary of a ditch, or other place of fmall 

 depth, which is to be emptied. 



The laving gun, which is ufed in fait -works from its fim- 

 plicity, comes next. It is a trough of five or fix feet in length, 

 made fmall at one end like a fpout, and gradually increafing to 

 the oppofite end, where it is about a foot or eighteen inches 

 fquare. The fmall end is fnpportedon pivots upon the bank 

 over which the water is to be raifed, and a lever is apphed to 

 it for a man to work it by. The large end of the trough 

 will dip into the water, when it defcends and becomes filled ; 

 but when Lfted the leaft above the horizontal poCtion, the 

 contained water will run along the trough, and be delivered 

 over the bank through the fpout. This machine is much 

 improved by making it double, or with two troughs, on the 

 oppofite fides of the centre ; thus when one afcends, the 

 other virill defcend fo as to raife up a conftant ftream, which 

 it muft, in this cafe, dehver at a fpout fideways, near to the 

 pivot or centre on which it plays. This double inachine 

 will raife a copious ftream of water, but is confined to fmall 

 heights of three or four feet. If the large end of the 

 trough has a valve opening into it to admit the water, it will 

 fill itfelf more readily. A machine which operates on the 

 fame principle as this, is called the fcoop-wheel, or tympa- 

 num, which is in fail feveral double laving machines ar- 

 ranged round the centre like a wheel. The advantage of 

 this wheel is, that it always moves in the fame direftion, 

 whereas the fimple machine requires a reciprocating 

 motion. 



The tympanum, or fcoop-ivheel, mentioned by Vitruvius, is a 

 great hollow wheel formed by a kind of barrel or drum 

 (as its name imports) : it is compofed of feveral planks 

 joined together, well caulked and pitched, and having a ho- 



rizontal axle with pivots at the ends, on which it turna. The in - 

 terior capacity of this drum is divided into eight equal fpaces, 

 by as many partitions placed in the direftions of the radii ; each 

 fpace or cell has an orifice of about fix inches in vpidth in the 

 rim of the drum or wheel. Thefe openings are fo ihaped, as to 

 facilitate the admiflion of the water ; moreover, there are 

 eight hollow channels running along the axle of the wheel and 

 contiguous to each other, each correfponding to one of the 

 eight large cells ; into thefe channels the water paffes out of the 

 cells juft mentioned, and after running along thechannels in the 

 axis of the wheel to a convenient diftance, it efcapes through 

 orifices into a refervoir placed juft under the axle. Thus 

 when the wheel is turned round, the water is elevated through 

 a vertical height equal to the radius of the hollow wheel. 



When the tympanum is ufed to raife water from 3 run- 

 ning ftream, it is moved by means of float -boards fixed on the 

 circumference, which are impelled by the ftream ; but when 

 it is employed to raife ftagnant waters, there is commonly a 

 fmaller hollow wheel fixed on the fttaft at the fide of the 

 tympanum, which is turned by men walking in it, as in the 

 old walking-crane. The chief defeA of this machine is, 

 that it raifes the water in the moft difadvantageous fituation 

 poflible, for the load of water is always towards the extre- 

 mity of a radius of the wheel, and the length of the effec- 

 tive lever which anfwers to it muft continually increafe as 

 the water is raifed through the whole quadrant, which the 

 water defcribes in paffing from the bottom of the wheel to 

 the altitude of its centre, fo that the power muft aft in the 

 fame manner as if it were applied to a winch or crank han- 

 dle, and cannot aft uniformly. 



The horn-iuheel was contrived to remedy this defeft : it 

 is fo called, becaufe the fegments which pafs from the cir- 

 cumferences of the large flat cylinder to its centre are not 

 ftraight radii, as in the former inftance, but are curved fpirally. 

 The fcoops, or mouths, by turns, dip into the water, and 

 as they rife up caule the water to pafs up the horn, or 

 curved fegment, until it is as high as the centre of the 

 wheel, and tlien it is difcharged into a trough placed under 

 the end of the axis, which is hollow, and has its pivots 

 fattened to a crofs. 



M. de la Faye has inveftigated the proper curves for the 

 fcoop fegments of this machine in the following manner : — 

 When we evolve the circumference of a circle by unwrapping 

 a ftring from the circumference, the end of the ftring will 

 defcribe a curve called the involute of the circle, of which 

 all the radii are fo many tangents to the circle, as is (hewn 

 by the ftring in its different pofitions whilft tracing the 

 curve, and likewife all the radii are refpeftively perpen- 

 dicular to the feveral points of the curve defcribed by the 

 end of the ftring. 



The greateft radius of this curve is a line equal to the 

 periphery of the circle evolved. The truth of this ftate- 

 ment is fhewn by geometricians, when treating of the gene- 

 ration of Evolute and Involute Curves. See thofe articles. 



Hence, having an axle, whofe circumference a little ex- 

 ceeds the height to which the water is propofed to be ele- 

 vated, let the circumference of the axle be evolved, and it 

 will make a curve which will be the involute of the circle, 

 as before mentioned. Now, let a number of pipes, or 

 trunks, be made exaftly with this curvature, and then put 

 together around the axle, in form of a wheel, fo that the fur- 

 ther extremities of thefe canals will fucceflively enter the wa- 

 ter that is to be elevated, whilft the other extremities abut 

 upon the ftiaft which is turned. Then, in the courfe of the 

 rotation of the wheel, the water taken in at the extremity 

 of each canal will rife in a vertical lijie, which is a tangent 



to 



