22 Olituary. 



the officials of the Imperial Board of Trade, he was entrusted by 

 them with certain delicate work in connexion with the official 

 standards of measurement. 



Grayson's most important achievement has been the construc- 

 tion of his engine for ruling diffraction gratings, a task to which 

 he devoted much time during several years. This apparatus, for 

 which a special room has been constructed at the University, 

 fitted up with elaborate precautions to secure absolute steadiness- 

 and freedom from temperature changes, is very fully described and 

 illustrated in a paper laid before the Eoyal Society of Victoria in 

 July 1917, wherein are also described in detail the methods of 

 construction, preparation of the diamonds, and other particulars 

 likely to be useful to other experimenters in the same class of 

 work, (Proc. Eoy. Soc. Vict., xxx. (N.S.), p. 44-95, pi. vi-xvii.) 



It was characteristic of Grayson that whatever work he- 

 achieved failed to satisfy him unless his results were at least equal 

 to the best obtained by other workers, and he assiduously studied 

 every process or piece of mechanism in the endeavour to improve 

 upon their procedure. Such microscopical preparations as he pro- 

 duced were always of high quality, his diatom type-slides, for 

 example, being in no way inferior to those of MoUer and Thum, 

 while his test-rulings and micrometers, as well as his photographs 

 of them, were, according to the opinions already quoted, in advance 

 of those of his predecessors. It is confidently believed that the 

 same judgnient will apply to his last and most important produc- 

 tion — the new engine for ruling diffraction gratings. 



W. M. Bale. 



