QL:EST/().\S 275 



153. Why are means for moderatinji; the l)y;lil iierossaiw for nil iiiicro- 

 st'opes with corrected condensers? 



154. What directions are to he ohserved in the use of the Al)he draw- 

 ing camera? 



155. What use may be made of the twiu-ohjcctive binocular magni- 

 fying 3.5 times, in drawing? 



156. How should microscopical drawings be normally reproduced? 



157. W^hy should the reference letters or numerals in a drawing be 

 inconspicuous? 



158. Name seven drawbacks to photography with the microscope. 



159. What are two of the optically best pieces of apparatus for photo- 

 graphy with the microscope? 



160. What are some advantages of the Siedentopf photographic 

 attachment? 



161. What color screens and plates are best for ordinary use with the 

 microscope? 



162. What is the aim in photography with the microscope? 



163. Name some ways of testing an objective for deterioration. 



164. Name a good test for the microscope objective. 



165. Describe the star test for an objective. 



166. W^hat kind of microscope did Galileo use? 



167. What kind of microscope did Leeuwenhoek employ for his 

 discoveries? 



168. When were the first compound achromatic objectives made? 



169. How is the correction for different cover-glass thicknesses made 

 (Ross and Wenham)? 



170. What did Wenham invent in 1850? 



171. When were water-immersion objectives most popular? 



172. Enumerate Abbe's chief microscopical inventions. 



173. What was the date of the first practical oil-immersion objectives? 



174. What invention was made public in 1SS(3? 



175. At what date was the Greenough binocular first made? 



176. What is the chief use of the special dark-field condensers? 



177. What arrangements often found on the microscope are deemed 

 by the writer superfluous? 



178. Mention some possible microscope improvements. 



179. Name four books or booklets suitable for beginners in micro- 

 scopy. 



180. What book is especially recommended for the practice of high- 

 power microscopy? 



181. What is the most important book on the theory of the micro- 

 scope, which is also of general interest? 



182. What book contains full sources of information on the theory of 

 optical instruments, and especially on the microscope? 



183. What is Nelson's method of critical illumination? 



