214 



The Hon. J. W. Strutt's Remarks on 



a 



) 



approx. 



(D) 



supposing the condition fulfilled as to the relative magnitudes of 

 L and a^. Now this form of (A) is perfectly legitimate, the 



4 

 value of — g being '405. In the formula (VII.) '405 is replaced 



1 ^ 

 by - or -430. 



' c 



But Dr. Sondhauss will naturally point to the comparison of 

 (X.) with the experiments of Wertheim, which he justly regards 

 as very satisfactory. I have examined the series of twenty-two 

 experiments with cylindrical tubes of circular form closed at one 

 end, and have calculated for comparison the results of (D) . It 

 will be seen from the annexed Table that, good as is the agree- 

 ment of the observations with (X.), it is still better (on the whole) 

 with (D). Indeed I must confess that the differences in some 

 cases, where &* is by no means small compared with L, are much 

 less than I should have expected. 



a. 



L. 



Diameter. 



n, observed by 

 Wertheim. 



n, calculated 



by Sondhauss 



from (X.). 



n, calculated 

 by me from 



(D). 



3371 



785 



80 



103 4 



102-9 



103-2 



3395 



500 





1580 



158-8 



159-7 



3413 



355 





219-2 



219-4 



220-8 



3371 



280 





272-4 



268-8 



2706 



3418 



157 





460-4 



451-8 



453-5 



3413 



1000 



60 



83-3 



83-1 



83-3 



3418 



640 





128 



128-3 



128-8 





340 





237 



233-7 



235 



3413 



1000 



48 



84 



83-6 



83-8 



3427 



350 





234-4 



231-2 



232-3 







25 



238-3 



237*4 



238-1 







20 



239-7 



238-8 



239-3 







11 



2415 



241-5 



241-8 







5 



2438 



243-3 



243-4 



3390 



206 



68 



3721 



361 8 



364-2 





116 



46-5 



640 



6276 



6310 





208 



43-5 



376-5 



374-2 



376-4 



3471 



487 ' 



200 



154-2 



152-6 



153-5 





243-5 





2741 



27 11 



269-5 





121-7 





416-9 



4550 



433-4 



3390 



305 



25 



270-1 



268-3 



269-2 







500 



20 



}66G 



]6Cr6 



166-8 



The foregoing Table shows that although (X.) represents 

 Werth elm's observations with considerable accuracy, yet.Helm- 

 holtz/s rational formula (I)) is on all grounds to be preferred. 



