46 THE MECHANICAL DESIGN OF MICROSCOPES. 



case of the microscope these grooves could be cut in the foot of 

 the instrument to rest upon and engage with three studs on the 

 table. This arrangement would be simple and cheap, and would 

 have the further advantage that it would not in any way interfere 

 with the use of the microscope in the usual way — the grooves when 

 not in use would not scratch the table top. In this simple way the 

 placing of th& lamp and the microscope in a fixed position with 

 respect to one another, would be secured. It would then only be 

 necessary to fix the mirror, as has been suggested by Mr. J. E. 

 Barnard, and the microscopist would, in a few seconds, be 

 able to ensure that a beam of light was being thrown accurately 

 along the axis of his microscope, a necessary condition, for ex- 

 ample, of the efficient use of the dark ground illuminator in bac- 

 teriological work. 



I have not been able to say much, ladies and gentlemen : the 

 time has been too short, but I hope that I have been able to say 

 something which will assist you to realise the national and far- 

 reaching importance of the subject with which we are concerned at 

 this Symposium to-day. 



