304 Number of Electrostatic Units in the Electromagnetic Unit. 



of the experiments on which Mr. ShioVs paper was founded, 

 and which has been in Mr. Bottomley's possession ever since, 

 the following statement of results: — 



" Deflections, a. Resistance, R " (in ohms). 



"(1) 44 15) ( 107-88 



(2) 42 45 y corresponding to -| 112-88 



(3) 51 39 J ( 82-88 



" Therefore we get," in C.G.S. units 



"(1) R tan «= 105-09, 



(2) R tan a =104-35, 



(3) R tan a= 104-785*, 



" and the mean value of 



"R tan a = 104-73." 



It is plain therefore that Mr. Shida, in copying down from 

 his notebook specimens of his numbers, inadvertently wrote 

 45° 15' in the first column of the table for the calculation of 

 R tan a, and in the second column gave 80 and 100 instead 

 of 75 and 80 respectively. The table ought accordingly to 

 stand : — 



*. r. R. Rtana. 



O / 



44 15 



75 



107-88 



105-09 



42 45 



80 



112-88 



104-34 



51 39 



50 



82-88 



104-76 



which gives Mr. Shida's average value of Rtana, viz. 104*73. 

 I do not think that Dr. Wright's letter calls for further 

 remark from me, except that, whatever may be the influence 

 of these "peculiar numerical aberrations" on the minds of 

 readers of Mr. Shida 's paper, we may take it for granted that 

 they had had no effect in leading Dr. Wright to believe that 

 u oversights had been made in other portions of the research," 

 or that precautions not mentioned "were probably omitted;" 

 for if these aberrations had been observed by Dr. Wright 

 before he wrote his note in the July number of the Philoso- 

 phical Magazine, he would probably not have forgotten them 

 when pointing out the trifling slip in misplacing the decimal 

 point in the statement of the electrostatic values of the cell 

 and battery. 



I have the honour to be, Grentlemen, 



Your obedient Servant, 

 Physical Laboratory, the University, ANDREW GrBAY. 



Glasgow, September 1881. 



* This value of R tan x, 104*785, has obviously been written by a slip 

 of the pen instead of 104755. 



