[From the Kensington Museum Hand Booh] 



LXXIX. Instruments connected with Fluids. 



IN countries where the fertility of the soil is capable of being greatly 

 increased by artificial irrigation, the attention of all ingenious persons is naturally 

 directed to devising means whereby the labour of raising water may be diminished. 

 Hence we find that in China and in India, but especially in Egypt, great 

 progress was made in the art of producing and guiding the motion of water. 



The first pump worked by a piston of which we have any account seems 

 to be that invented by Ctesibius of Alexandria, about 130 B.C. 



The construction of this pump, as described by Vitruvius, resembles that 

 of the modern fire-engine. It had two barrels, which discharged the water 

 alternately into a closed vessel, the upper part of which contained air. This 

 air-chamber acted as a reservoir of energy, and equalised the pressure under 

 which the water was emitted from the discharge pipe. 



Hero, a scholar of Ctesibius, invented a number of ingenious machines. He 

 delighted in curious combinations of siphons, by which fountains were made to 

 play under unusual circumstances. We should call such machines toys, but though 

 to us they have no longer any scientific value, we must regard them as among 

 the first instances of apparatus constructed not in order to minister directly 

 to man's necessities or luxuries, but to excite or to satisfy his curiosity with 

 respect to the more unusual phenomena of nature. 



From the time of Ctesibius and Hero to that of Galileo (1600) pumps were 

 constructed chiefly for useful, as distinguished from scientific, purposes, and con- 

 siderable skill was developed in the art of forming the barrel and piston so 

 as to work with a certain degree of accuracy. 



Galileo shewed that the reason why water ascends in a sucking pump is 

 not that Nature abhors a vacuum, but that the pressure of the atmosphere 

 acts on the free surface of the water, and that this pressure will force the 



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