XII. ELECTRON MICROSCOPY 405 



techniques for specimen preparations that will peiinit him to obtain 

 that information from the electron microscope imafi;('s. Finally, he 

 will assist in the interpretation of the imajics obtained, his main 

 obligation in this onnectiou heinj;' the prevention of their being mis- 

 interpreted. 



Expense. It is obxious Iroui (he aboNc that the cfticiciit use of 

 an electron microscope in\-ol\<'s considerable expense beyond the 

 initial outlay. While the actual amount of money spent by the 

 different electron microscope groups already in existence varies 

 greatly, it appears to this author that prospective electron microscope 

 users can expect the annual cost of such an organization to be at least 

 equal to the initial cost of the instrument. It should be pointed out 

 that this estimate includes all hidden, as well as apparent, costs. 

 Actually, the total cost is not always the significant one, since in 

 some organizations much of the money spent for the maintenance of 

 an electron microscope laboratory would be spent in any case. In 

 these cases, the major expenditure is that involved in the actual 

 purchase of the electron microscope and the necessary auxiliary equip- 

 ment. 



4. Skill Involved in Operation of the Inslrunient 



In the organization suggested above, the research worker who 

 has need of an electron microscope does not have to l)e familiar with 

 the technical details of the operation of the instrument, though ob- 

 viously he should make himself familiar with the fundamental prin- 

 ciples involved and with the significance of the images obtained. If, 

 however, this ideal situation is not possible and the research worker 

 finds it necessary to operate the electron microscope himself, it is 

 desirable that he first devote a considerable amount of time familiariz- 

 ing himself with the general manipulation of the instrument. 



Learning to operate an electron microscope is in many ways analo- 

 gous to learning to drive an automobile. The simple manipulations 

 necessary to make the device fimction are extremely easy to learn in 

 either case, particularly if the individual has some fundamental 

 knowledge of the principles involved. On the other hand, the new 

 automobile driver is not considered to be a good one until Ixe has 

 di'iven many thousands of miles on all types of roads and has en- 

 countered many traffic problems. Similarly an electron microscope 

 operator does not become proficient at producing high quality micro- 

 graphs or at recognizing defects and their causes until he has made, 



