DR. A. E. H. TUTTON 207 



scope, are as clear as the interference bands in the interferometer of the 

 Comparator, and the writer expressed hopes in his memoir to be able 

 to carry out with their aid the determination, by this original method, 

 of the exact nnmber of red cadmium wave-lengths in the British 

 Yard. Such a determination would, indeed, be quite simple and 

 straightforward, with the proviso that an adequate supply of the 

 rulings required for the stepping off process could be obtained. 



The writer also hopes to use them as fiducial marks in connection 

 with interferometric fine-measurement in general, and a General 

 Interferometer, involving the same type of travelling fine-movement 

 microscope as those (the pair) on the Comparator, is being con- 

 structed for him for the purpose at this moment. 



The breaking out of the great war, and now the unhappy death 

 of Prof. Grayson, have delayed the possibility of further work on 

 the subject, and as doubtless other workers in high power microscopy 

 are also at present unable to carry out their own particular researches 

 for which the higher rulings are essential, the writer considers it 

 desirable that the position shall be discussed at this Symposium of 

 Microscopists. 



The writer's suggestion is that the Symposium should address 

 to the Governing Body or Council of the University of Melbourne a 

 letter of condolence, expressing firstly the unanimous opinion of the 

 great body of Microscopists and Scientific workers here assembled 

 of the very great loss which the University has suffered by the demise 

 of Prof. Grayson; and, secondly, the hope that the University will 

 do all that is possible to ensure that Prof. Grayson's ruling machine 

 shall still be available for the production of the '"' Grayson Rulings." 

 It may be that Prof. Grayson had trained one or more members of 

 his staff in his method, and if so it should not be difficult to arrange 

 for the most highly desirable continued production of the rulings. 



The writer took the opportunity of mentioning the matter to 

 General Sir John Monash, the gallant Commander of the Australian 

 Forces, and a member of the Governing Body and Council of 

 Melbourne University, on his recent visits to London and Oxford on 

 the conclusion of the War, and he kindly undertook to go into the 

 question on his return to Melbourne, Possibly General Monash's 

 relative. Dr. Rosenhain, whom we know to be interested so keenly in 

 the subject from the microscopical point of view, and who has intimate 

 connections with Melbourne and its University, will also be inclined 

 to assist in carrying the subject further. 



The continued production of the Grayson Rulings, especially 

 those of the 40,000 to the inch spacing, is so important a matter 

 that the writer has felt sure that the Symposium would wish hira 

 to bring it forward. 



