I90 EXPERIMENTS 



gy fiibftance within the tube being broken and 

 divided into portions nearly equal. The fol- 

 lowing phaenomena will clearly prove that 

 this is the cafe. 



' It fometimes happens, that the fcrew and 

 the tube break precifeiy above the pifton i*, 

 wdiich remains in the barrel c, [fig. 3.] Then 

 the tube inilantly fliuts ; and, by contrading, 

 affumes a conical figure above the extremity of 

 the fcrew, ji^ This is a demonftration that it 

 is there very elaftic ; and the manner in which 

 it accommodates its figure to that of the fub* 

 ftance which inculudes it, when the latter un- 

 dergoes the fmalleft change, proves that it is 

 every where equally elaftic' 

 M. Needham hence concludes, that it is na- 

 tural to imagine that the total adion of this 

 machine is occafioned by the fpring of the fcrew* 

 But, unfortunately, he proves, by feveral expe- 

 riments, that the fcrew is acted upon by a power 

 refiding in the fpongy part : As foon as the 

 fcrew is feparated from the reft of the machine, 

 it ceafes to ad, and lofes all motion. The au- 

 thor draws the following conclufion from this 

 fmgular phaenomenon. 



' If I had i'een,^ fays he, ' thefe pretended ani- 

 ' malcules in the femen of living animals, I fhould, 



* perhaps, have been able to afcertain whether 

 ' they are really animated beings, or only pro- 



* digioufly fmall machines, which correfpond in 

 ' miniature to the larger veflels of the calmar.' 



From 



