THE LAWS OF FLUID RESISTANCE. 



99 



(see Fig. 6), since the differences of pressure at different 

 points depend on the differences of sectional area at 

 those points, by a law which is exactly the same in an en- 

 larging as in a contracting pipe, the points which have 

 the same sectional areas will have the same pressures, 

 the pressures at the larger areas being larger, and those at 

 the smaller areas smaller. 



FIG. 7. 



Precisely the same result will follow in the case of an 

 enlargement followed by a contraction (see Fig. 7). 



Were water a Motionless fluid these propositions could 

 be exactly verified by experiment as follows. 



Figs. 8 and 9 show certain pipes, the one a contraction 

 followed by an enlargement, the other an enlargement 

 followed by a contraction. At certain points in each pipe 



LEVJZJL 

 D 



FIG. 



there are small holes, communicating with vertical gauge- 

 glasses. The height at which the fluid stands in each of 

 these vertical glasses of course indicates the pressure in 

 the pipe at the point of attachment. 



In Fig.. 8 the sectional areas at E and P are equal to 

 one another. Those at C and K are likwise equal to one 



H 2" 



