ELECTRICAL A(^TIVITY OF ORE BODIES. 



355 



fore, were employed. In all other respects, however, the former plan (see 

 page 328) was rigitUy adhered to, with such slight variations, of course, as 

 the different methods rendered necessary. 



Results, — The following table, containing- the potential of the consecu- 

 tive points on the 600-foot level — that of No. VIII. being arbitrarily put 

 equal to zero, as before — will be intelligible without much further explana- 

 tion. The results of the different methods are arranged in parallel colunms, 

 and in the order in which they were described. For the sake of comparison 

 those obtained in the former survey are also added, and a final column 

 shows the difference between the two. 



Table XIX. 



The results obtained by different methods present throughout a fair 

 agreement, Avhen it is remembered that errors amounting to a few thou- 

 sandths of a volt are introduced by circumstances beyond the observer's 

 control. Between the mean of the new and the mean of the former results 

 there are a number of annoying discrepancies. In part, though by no means 

 wholly, these are due to a diffei-ence in the values of the standard electro- 

 motive force employed in the two cases. With the knowledge at present. 



