WATER. 



■which immediately furrounds it, until it has put that water 

 in motion with nearly the fame rapidity as the rope, and 

 then fuch portion of water will accompany the rope ; but 

 this cannot take place without communicating a flower 

 motion to a much larger quantity of water, which will alfo 

 accompany the rope with a flower motion ; but being too 

 far removed from the rope to have its motion accelerated, 

 or even maintained, its velocity will continually decreafe, 

 until it ceafes to afcend, and then it will begin to run back. 

 But this is to be underftood only of that part of the water 

 which is too far diilant from the rope to have its motion 

 fully maintained by the lateral adlion of that water which 

 is nearer to the rope, and which moves with nearly the fame 

 velocity as the rope. If the rope is examined at the point 

 where it rifes above the furface of the water, it will be 

 found to be furrounded by a column of water which is of a 

 confiderable fize at the bafe, but diminifties as it rifes up- 

 wards, fomewhat in the form of a trumpet, fo that at a few 

 feet in height it is but little larger than the rope. This 

 column of water is compofed of feveral laminve, each moving 

 with a different velocity : for inllance, the interior part 

 moves nearly as quick as the rope, the water which is more 

 diftant from the rope moves flower, until there muft be a 

 part in which the water remains immoveable, and all the 

 water which is beyond this, and on the outfide of the 

 .column, runs downwards, and falls back into the well. On 

 this account, the machine lofes a confiderable part of the 

 power which is applied to it without producing an adequate 

 €ffea. 



This machine was invented by the Seur Vera, in France. 

 A machine was made by him with a wheel three feet dia- 

 meter, and a hair-rope of half an inch diameter, the well was 

 ninety-five feet deep. A man could turn the wheel fixty 

 times ^fr minute, which gives a velocity of five hundred and 

 fixty-five feet^fr niuuite for the rope. It brought up fix 

 gallons per minute, but was fevere labour for one man. 

 When the wheel made fifty turns, and the rope moved four 

 hundred and feventy-one feet per minute, the machine ftill 

 raifed a confiderable quantity of water ; but if the motion 

 was reduced to thirty turns, or two hundred and eighty-two 

 feet per minute, it brought up fcarcely any water. A rope 

 of hair is preferable to hemp, becaufe it is lefs fubjeft to 

 decay ; and when a hemp-rope begins to rot, it commu- 

 nicates a taint to the water. 



The Sucking-Pump has a valve at the bottom of the bar- 

 rel, and alfo another valve in the pifton, vifhich is called a 

 bucket, becaufe it brings up the water before it. This 

 pump does not raife water when the bucket is let down, but 

 only when it is drawn up, which is in fome cafes an incon- 

 venience ; and another objeftion is, that it cannot raife 

 water to a greater height than the place where the power is 

 applied, becaufe there muft be an opening for the pump-rod 

 to come out at, and the water would flow out at the fame 

 opening, if it was raifed as high. This inconvenience is 

 remedied by 



The Lift-Pump, which has a valve in the bucket, the fame 

 as the fucking-pump, but it differs from it in the manner of 

 communicating the force to the pifton or bucket : one way 

 of effefting this is to make the barrel open at the lower end, 

 and the rod from the bucket, inftead of being fixed to the 

 upper fide of the bucket, is fixed to the lower fide, and 

 comes out beneath the furface of- the water in which the 

 barrel is immerfed. Rods are jointed to tliis, and rife up pa- 

 rallel to the barrel, in order to be attached to the lever by 

 which the pump is to be worked ; the fixed valve is placed 

 at the top of the barrel above the bucket ; this is the old- 

 fafhioned lift-pump. 



The Lift-Pump -with a Stuffing-box, called fomctimes a 

 jack-head pump, is exaftly the fame as the fucking-pump, 

 except that the top of the barrel is covered by a lid, which 

 has a hole in the centre for the rod to pafs through : the 

 rod is made very fmooth and true, and the hole is fo formed 

 as to contain collars of leather, which fit clofe round the rod, 

 and prevent the efcape of any water by the fide of the rod. 

 The water mounts up a pipe which communicates fideways 

 with the upper part of the barrel. 



Another form of lift -pump has been recently introduced, 

 in which the pifton is folid, having no valve in it, and the rod 

 pafTes through a ftufRng-box or collar of leather in the top 

 of the barrel, the bottom of the barrel being open. Two 

 pipes are made to communicate fideways with the barrel at 

 the upper part, one of which brings water from the well 

 into the pump when the pifton defcends, and has a valve 

 in it to prevent the return of the water ; the other pipe 

 conveys the water away from the barrel when the pif- 

 ton is drawn upwards, and this is likewife furnifhed with 3r 

 valve to prevent the return of the water. 



One advantage of tliis kind of pump is, that both valves 

 are fituated in boxes near the top of the barrel, and can be 

 examined and repaired at any time by taking off the doors 

 or covers of the boxes ; but in pumps where there is a valve 

 at the bottom of the barrel, it fometimes happens that the 

 valve fails, and requires to be repaired, when the water in the 

 well ftands higher tlian the cover or door of entry to the 

 valve : in this cafe, fome other means muft be ufed to reduce 

 the water in the well, or elfe the pump mulf be drawn up 

 out of its place, wliich, in large works, is very difficult. 

 Another advantage is, that the apertures of the valves may 

 be made of any required dimcnfions to let the water pafs 

 freely through them ; but wlien tlie water muft come up 

 through a valve in the bucket or pifton, the paflage through 

 the valve muft necefl'arily be much fmaller than the barrel, to 

 allow a proper lodgment all round for the valve and alfo 

 for the leathers. 



The Force-Pump. — This is made with a fohd pifton, like 

 the laft, but the barrel is open at the top, where the pifton-rod 

 comes out. There is a valve at the bottom of the barrel to 

 admit the water into it, and a pipe, which turns fideways 

 out of the barrel at bottom, and has a valve to prevent the 

 water returning into, the barrel, to convey the water to what- 

 ever place it is to be forced to. The force-pump raifes 

 water only when the pifton is prefled down, whereas the 

 lift-pumps and fucking-pumps raife the water when the 

 buckets are drawn up. 



The Lift and Force-Pump of M. De la Hire. — This is the 

 union of the two laft pumps in one, for both thefe pumps 

 work with a fohd pifton, and the barrel of the force-pump 

 is open at top, and the barrel of the lift-pump is open at 

 bottom ; hence the fame barrel and pifton may be made to 

 ferve for both, Tliis pump throws up water equally when 

 the pifton-rod is drawn up or wlien it is forced down, and 

 is moft proper for the double-afting fteam-engine. It has 

 the advantage of raifing twice the quantity of water that 

 any of the other pumps will raife, and with the friftion of 

 only one pifton ; alfo the v.alves admit of being made of fuf- 

 ficient fize to allow the paffage of the water without any 

 imneceffary refiifance. 



Force-Pump ivilh a folid Plunger. — This was invented 

 by fir Samuel Morhmd, and does not differ from the force- 

 pump laft defcribed, except in the manner of fitting the 

 pifton to the barrel. Inftead of the barrel being bored truly 

 cyhndrical withinfide, and the piilon fitted into it fo as to Aide 

 up and down, and provided with leathers to make a clofe fit- 

 ting, the pifton is made of a cylindrical form, and very nearly 



