8 



A. TANAKADATE. 



plate of tlie theodolite for declination observation, or to the 

 base of Y's for deflection experiments, by working the differential 

 screw at the center. (See pi. in front page.) 



3. Use of autocolli mating telescopes, which makes the in- 

 strument more compact. 



4. Cylindrical form of vibrating magnet which facilitates 

 the use of transporter. 



5. The transporter with which the magnet can be carried 

 from one position to another on deflection bar or reversed in 

 direction with great ease, without the danger of imparting heat 

 from the hand of the observer. 



Fio:. 1. 



It may be remarked here that Mr. Ch. Chree's objection 

 to the Kew pattern of deflection bar was looked into in 1887 

 already, though not expressly stated. From the photograph in 

 the front page, it will be seen that the correction arising from 

 the flexure of the bar is very small in our design. 



6. The use of the dip circle box for vibration box : for 

 this purpose two Y's were provided on the base plate of the 

 box. When the bar magnet was laid on those Y's its axis was 

 horizontal and it was so adjusted in azimuth that its direction, 



