354 Mr. F. M. Lidstone on the 



Summary. 



The factors of inertia of fluid and friction of perilymph 

 against the walls of the scalce, with the variation in elastic 

 tension of the basilar membrane and organ of Corti, must 

 have considerable influence in analysing complex pressure 

 variations, and such factors are capable by themselves of 

 analysing coarser pressure variations such as the irregular 

 contractions constituting a slow muscular movement. 



This process of analysis would satisfactorily account for 

 summation and difference tones. 



XXXV. Notes on the Measurement of Absolute Viscosity. 

 By Frank M. Lidstone *. 



IT appears to have generally escaped notice, that in any 

 form of absolute viscometer where a variable head 

 obtains, it is not strictly accurate to use the mean head 

 when computing the viscosity. 



When the difference between the initial and final heads 

 is at all large as compared with the mean head, the error 

 introduced becomes far from negligible. 



If we take the general formula of Poiseuille, 



Kth V Y 



V= ~T ° r t = Kh' 



Here h stands for the head, V for the volume, and t for 

 the time of efflux. K represents the remainder of the 

 constants, with which we are not at present concerned. 



By taking all the heads, from the initial to the final, 

 summing the times, and integrating the expression we get 



**-*-K(H-F)J E *' 



where H is the initial and F the final head. This gives us 

 in place of the original equation 



Kj(H-F) 

 v = w — 



* Communicated by the Author. 



