138 



Scientific Proceedings, Royal Dublin Society. 



magnetic moment was measured by the usual end-on magnetometric method r 

 and the distance between the poles measured in each case as follows : — The 

 brass frame containing the laminations was placed on a horizontal table in a 

 magnetically east and west direction, and a small compass needle, 1 centimetre 

 long, mounted on a horizontal axis and encased in a brass and glass frame, 

 was moved along the magnet until it stood vertically. This operation was 

 done for each end of the magnet, and the distance between the two marks 

 was taken off by means of a pair of drawing compasses made entirely of brass 

 and measured on a millimetre scale. In this way a difference of one-quarter 

 of a millimetre in the distance could be read. Each time a lamination was 

 added, the bundle was re-magnetised in the same direction in a magnetic field 

 of about 1200 units. 



Table I. 



Table II. 



