384 



son and E. 



W. Morley- 



—Influence of 



X. 



V. 





o-oo 



1-000 





•20 



•993 





•40 



•974 





•60 



•929 





•80 



•847 





•90 



•761 





•95 



•671 





1-00 



•ooo 





The curve constructed with these numbers coincides almost 

 perfectly with the curve 



.165. 



v=(l— O 



/» 1 .165 n 



The total flow is therefore 2?r/(l— x*) xdx = _, , . The area 



e/o 1*165 



of the tube being tt, the mean velocity = t ,twj °^ ^ ae Maxi- 

 mum ; or the maximum velocity is 1*165 times the mean. 

 This, then, is the number by which the velocity, found by 

 timing the flow, must be multiplied to give the actual velocity 

 in the axis of the tube. 



Formida. 



Let I be the length of the part of the liquid column which is in 

 motion. 

 u = velocity of light in the stationary liquid. 

 v =. velocity of light in vacuo. 

 8 = velocity of the liquid in the axis of tube. 

 Ox = acceleration of the light. 



The difference in the time required for the two pencils of 



I l 2l8x 



light to pass through the liquid will be 2 T7n = — r 



very nearly. If A is the double distance traveled in this time 

 in air, in terms of X, the wave-length, then 



. Mdtfx . Xv 



A = — = whence x = 



Xv 4ln*d ' 



X was taken as '00057 cm. 



V = 30000000000 cm. 



n 2 = 1-78. 



The length I was obtained as follows : The stream entered 

 each tube by two tubes a, b (figs. 1, 2) and left by two similar 

 ones d, c. The beginning of the column was taken as the in- 

 tersection, 0, of the axes of a and b, and the end, as the inter- 

 section, </, of the axes of d and c. Thus l=oo'. A is found 

 by observing the displacement of the fringes ; since a displace- 

 ment of one whole fringe corresponds to a difference of path of 

 one whole wave-length. 



