586 WEBEB ON A TRANSPORTABLE MAGNETOMETER. 



Fig. 10. represents the theodolite with the verification telescope: two scales 

 are seen, one of which, a, is applied in such manner that its middle 

 corresponds to the prolongation of the vertical axis of rotation of the 

 theodolite ; the other, h, c, is attached in front of the object-glass of the 

 verification telescope. It is very narrow, in order to intercept the less 

 light. 



Figs. 11, 12 and 13. are explained in the text. 



W. Weber. 



I 



