9G 



LECTURES TO SCIENCE TEACHERS. 



not elastic), and to be fastened at the ends, the pipe, 

 although flexible, will not tend to be disturbed in its shape 

 by the inertia of the fluid which is running through it ; 

 because the fluid does not cause any lateral force, but only 

 a longitudinal stretching force, and that the same in 



FIG. 4. 



amount at every point. And this will clearly be so in a 

 pipe of any outline, because any curve may be made up by 

 thus piecing together short bits of circular arcs of appro- 

 priate radii. 



FIG. 5. 



Let us then take a flexible pipe having the two ends in 

 the same straight line, but pointing away from one another, 

 as in Fig. 5, the intermediate part being of any outline you 

 please. If the ends are fixed we have seen that the flow of 



