A form of stand which is now very popular is 

 called the Continental pattern, from the fact that it 

 was originally made on the continent of Europe, and is 

 a combination of the Jackson and the Ross models. 

 The coarse adjustment, when consisting of a rack and 

 pinion, is placed close to the tube while the fine adjust- 

 ment is placed in the arm. 



Tube Length. The Continental form, Fig. 25, 

 which is quite generally used in all countries, has a 

 short tube from 160.0 to 170.0 mm. (6.3 to 6.7 inches) 

 whereas in England the long tube from 216.0 to 250.0 

 mm. (8.5 to 10 inches) is still retained to a consider- 

 able extent. The short tube contracts the height of 

 the instrument, this being the vital point in the con- 

 struction of the Continental stand. 



Until recently this subject was given little attention, 

 each maker following a standard which he had adopted 

 for himself. The injurious influence of this diversity 

 was not appreciated by the public, as it was not 

 acquainted with the products of different makers, until 

 Prof. S. H. Gage made it the subject of a paper before 

 the American Microscopical Society and, as a result of 

 his inquiries, prepared the table of standards, Fig. 26, 

 followed by the different makers. 



Acting on his suggestion a committee was appointed 

 to consider this subject, as well as that of eyepiece, 

 objective and thickness of cover glass, to which we will 



35 



