180 



KNOTT AND TANaKaDATP, 



form of the theodolite. The central part of the stage (a a) rose up 

 to a height which fell somewhat sliort of the level of the Y's, and 

 ended in a socket intended for the insertion of the base of the mng- 

 netometer proper. The last essential part of the stage was a stout 

 brass bar ( 6 6 ) running through between the Y pillars. From its- 

 ends rose uprights, to one of which was fixed the telescope nnd scale 



t'ig. 1. 



(^ natural size). 



(^ natural size). 



used in the readings, and to the other a lamj) for night work, which 

 also played the rôle of counterpoise. The fixing of the stage to the 

 base of the theodolite instead of to tlie Y's Avas effected by means of 

 a clamp (^) attached to the brass ])ar and attachable to the rim of the 

 theodolite. In this wav the stage could be clamped to either base or 

 Y's, singly or together, as occasion might require. 



