WATER. 



confequtnce the two grooves will be eight inches apart from 

 middle to middle, meafuring parallel to the length of the 

 cylinder, Into thefe grooves drive and fallen pieces of 

 board, fo as to form radii or feftors of a circle of eighteen 

 inches and a half diameter, and fo moulded as to be a little 

 upon the twift, to anfwer the different inclinations of the 

 helix, at the different diftances from the centre. Thefe 

 pieces being jointed together, and to the axis, fo as to fill 

 the whole groove from one end of the axis to the other, 

 form a double fcrew ; then apply narrow boards longitu- 

 dinally, reaching from one end of the fcrew to the other. 

 The boards fhould be about four inches broad, and formed 

 concave withinfide, anfwerable to a circle of eighteen inches 

 diameter. Thefe boards are marked one by one at the 

 places where they touch the fpiral boards, and are then 

 grooved about a quarter of an inch, to admit the ends of 

 the radius pieces which form the fcrew. When all the boards 

 are put together they form a cylinder of eighteen inches 

 diameter, which is hooped on the outfide, in the manner of 

 a tub or call< ; and in order that the hoops may properly 

 drive on the outfide, at the fame time that the infide forms a 

 complete cylinder, the longitudinal pieces are made rather 

 thicker in the middle than at the ends. 



Archimedes' fcrew may be ufed for other purpofes than 

 railing of water. It might be adapted with advantage in 

 raifing cannon-balls from a Ihip to a wharf, and with the 

 addition of a bevel-wheel or two and their pinions, might 

 be worked either by men or horfes. Sometimes Archi- 

 medes' fcrew inftead of being worked by men at a winch, 

 is turned by means of float-boards fixed on the circum- 

 ference of a wheel placed at its lower end, upon which a 

 ftream of water afts. If the water has a moderate fall, it 

 will have fufEcient eifioacy to turn two fcrews, one above 

 another. The top of the lower fcrew and the bottom of 

 the upper fcrew may aft one upon the other, by means of a 

 wheel upon each, with an equal number of teeth taking 

 into each other. In this cafe the upper fcrew will turn in a 

 contrary direftion from the lower, and confequently the 

 fpiral lube mufl be wound about the cyhnder in an oppofite 

 direftion. A folid wheel, or a light wheel with a heavy 

 rim, turning upon the middle of the fcrew as an axis, will 

 operate like a fly, and in fome cafes be very ufeful. 



Mr. Smeaton made a machine to raife water by an Archi- 

 medes' fcrew for the royal gardens at Kew, which was on 

 a large fcale. The fcrew was twenty-four feet long, two 

 feet fix inches in diameter, and raifed the water perpendicu- 

 larly fourteen feet nine inches. The central cyhnder, or 

 fhaft of the fcrew, was ten inches diameter ; the diflance be- 

 tween the threads, including the thicknefs of the hehx, was 

 twelve inches and a half ; and as there were two fpiral paf- 

 fages, each fpiral advanced twenty-five inches along the cy- 

 linder at every turn ; each fpiral contained twenty-feven 

 quarts at every turn, the fcrew therefore gave out fifty-four 

 quarts at every turn which it made. 



This fcrew was turned by means of a trundle or pinion 

 from a horfe -wheel, with the intervention of two moveable 

 joints, to change the direftion of the axis from the hori- 

 zontal to the direftion of the axis of the fcrew, which was 

 inclined at an angle of about thirty-eight degrees to the 

 horizon. The diameter of the horfe-track was twenty- 

 five feet, half of which was the length of the effeftive 

 lever upon which the horfes afted. The great cog-wheel 

 on the axis of the levers was fourteen feet diameter, with 

 144 cogs, and the trundle which it turned twenty-three 

 cogs, fo that the fcrew made about fix turns for one of the 

 horfe-wheel. 



This machine was worked by two hght horfes, with very 

 Vol. XXXVIII. 



great eafe, and they made three turns *.r minute ; but if at 

 all urged, could make the fcrew turn twenty turns pir mi- 

 nute, and at that rate of working raifed 300 hogfheads /^r 



ThelVater.fcre'w, defcribed in our article Screw, does 

 not differ from the fcrew of Archimedes in its principle 

 but as the fcrew turns round within a fixed barrel, the water 

 is liable to leak back in part. 



Draiving Water by Buckets — The methods which we have 

 hitherto defcribed are only adapted to raife water to fmall 

 elevations ; but by means of buckets, water may be drawn 

 from very great depths. The raofl fimple cafe is that of a 

 man with a bucket or other veffel in his hand, ftooping down 

 to lower the empty bucket into a pond, as low as he can 

 reach, and drawing it up full of water. 



The firll improvement which would occur would be to 

 fufpend the bucket by a rope, and draw it up by means of a 

 long lever, or otherwife, if the depth was greater, by con- 

 tinuing the rope over a pulley, fo that the man could eafily 

 draw the end of it ; and this would be farther improved 

 when two buckets were fufpended at the oppofite ends of 

 the rope or chain, fo that one being drawn up full of water 

 an empty one would be let down at the fame time. This 

 method is apphcable to the deepeft well, and is very etfec- 

 tive. The addition of a windlafs and crank would be a 

 fucceffive improvement, and could be made to aft either 

 fingly, to draw up one bucket, or double, to let down an 

 empty bucket at the fame time it drew up another loaded 

 with water. 



The drawing up of a bucket by a rope and pulley is 

 lo fimple and obvious as to need no explanation. The 

 bucket fiiould be of fuch a fize that it will not weigh above 

 twenty.fix pounds, and will therefore contain nearly half a 

 cubic foot of water. For although a man could with eafe 

 raife a much greater weight, yet he would be unable to 

 draw It up fo quickly, or to work at it throughout the 

 day ; and what he would gain by the increafed quantity of 

 water, he would lofe in the time which it would require to 

 draw up the bucket, and in the time he would require to 

 reft himfelf from his fatigue. If the rope is condufted ho- 

 rizontally, and the man takes it over his Ihoulder and walks 

 along the ground, his force will be applied in a much more 

 effeftive manner than by fimply hauhng the rope over a pul- 

 ley ; and a horfe may be applied in the fame manner with a 

 larger bucket, and there is perhaps no better mode of ap- 

 plying the force of a horfe for a deep well. The bucket 

 fhould not in this cafe weigh above a hundred and twenty 

 pounds, or it muft not contain above two cubic feet to 

 enable the horfe to draw it with that velocity which is moft 

 natural to him. 



When a windlafs is employed to wind up the rope, the 

 winch or crank, which is applied to the axis of it, can be 

 made much larger than the radius of the windlafs, and in 

 confequence the power may be increafed fo much that a 

 larger bucket may be drawn, which is fome advantage, be- 

 caufe lefs time will be loft in flopping to fill and empty the 

 bucket, otherwife nothing is gained in drawing up a large 

 bucket, becaufe it muft move flower in proportion to its in- 

 creafed weight ; but in all cafes the length of the handle 

 fhould be about fourteen or fixteen inches, to enable a man 

 to turn it with eafe, and the weight of the bucket mufl be 

 fo adapted to the fiz.e of the windlafs, that the power re- 

 quired at the handle will not be above thirty pounds or even 

 twenty-five pounds, if a man is to work continually for fix 

 or eight hours in a day. For example, fuppofe the bucket 

 is about forty-fix pounds weight, and the handle fixteen 

 inches long, then as 46 is to 25, fo is 16 to 8| nearly ; from 

 ^ which 



