402 JAMES HILLIER 



instruments have been made by the Radio Corporation of America 

 (RCA) since 1940 and have been improved continuously. 



These instruments can be divided roughly into two classes; first, 

 the research instrument, which has rather high resolving power rang- 

 ing, for various makes, from 10 to 2 irifx, and the smaller instrument, 

 which is simpler to operate but more suited to routine test work, hav- 

 ing a resolving power of the order of 10 m/x. 



It is not possible at the present time to discuss the relative merits 

 of the different designs. Only partially complete information is 

 available in this country concerning the European designs, which 

 have many novel features that have not yet been tested by widespread 

 use in laboratories outside those of the designers. From the pub- 

 hshed micrographs produced by the different instruments, it is quite 

 apparent that the most recent RCA instrument has the highest 

 resolving power, though the instrument designed by le Poole as the 

 basis of that to be produced by Philips compares quite favorably with 

 it. At present the RCA electron microscope (Universal Model) 

 appears to have other advantages in the basic nature of its design, 

 which make it considerably easier to adjust and operate, and in the 

 advanced design of the power supplies. 



3. Electron Microscope Laboratory 



At present, and probably for some time in the future, the electron 

 microscope will be used as a research tool by research laboratories 

 investigating a variety of problems. It has been the experience 

 of such laboratories that the best use can be made of the electron 

 microscope if it is set up as a separate service laboratory operated 

 by a small group of experienced electron microscopists who at the 

 same time have interests in common with those of the other sections 

 of the laboratory. As has already been pointed out, it has been 

 shown to be unsatisfactory^ to have an electron microscope in a 

 laboratory available for use by the individuals concerned with the 

 actual research problems. In the cases in which such a system 

 has been tried it has been found that none of the individuals using 

 the instruments obtained sufficient experience with it or understand- 

 ing of it to obtain the full benefit of its use. Furthermore, the main- 

 tenance of the instrument itself became a haphazard matter, which 

 generally resulted in its slow degeneration. 



In the following will be described what appears to be a suitable, 

 if not ideal, arrangement of an electron microscope service laboratory. 



