respecting Sound and Light. 



113 



that in several instances a greater height of the first gage pro- 

 duced a less height of the second : this arose from the nearer 

 approach of the apex of the cone to the orifice of the tube, 

 the stream losing a greater portion of its velocity by this diver- 

 gence than it gained by the increase of pressure. At first sight, 

 the form of the current bears some resemblance to the vena 

 contractu of a jet of water : but Venturi has observed, that in 

 water an increase of pressure increases, instead of diminishing, 

 the distance of the contracted section from the orifice. Is it not 

 possible, that the facility with which some spiders are said to 

 project their fine threads to a great distance, may depend upon 

 the small degree of velocity with which they are thrown out, so 

 that, like a minute current, meeting with little interruption 

 from the neighbouring air, they easily continue their course for 

 a considerable time ? 



Table v. 



A 



1. 



2. 



3- 



3.8 



B 



C 



C 



C 



C 



1. 



2. 



3- 

 4- 

 5- 

 6. 



7- 



8. 



9- 



10. 



15- 

 18. 



20. 



.1 

 .12 



■17 



.2 



.25 



.30 

 ■35 



■37 

 ■39 



.40 



•50 



.1 



.12 

 .25 



•4 

 ■5 

 .52 



•54 

 ■56 

 •58 

 .6 



•7 



.1 



.2 



•3 



•4 



■5 



.6 



■5 



The diameter of the tube .07. 

 A is the distance of the liquid from 

 the orifice. B, the pressure. C, 

 the diameter of the surface of the 

 liquid displaced. 



MDCCC. 



Q 



