852 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



"Midget" Microscope. — Fig. 156 also shows this Microscope to 

 the same scale as the previous one. It was made by Mr. S. Holmes, 

 and is only 4| inches high with a diameter of body-tube of less 

 than ^ inch. It is probably the smallest working instrument ever 

 made. 



Beck's Histological Dissecting Microscope. — This instrument 

 (Figs. 157, 158) combines a compound with a simple and dissecting 



Microscope, the stout arm holding the 

 Fig. 157. single lenses being made so that a com- 



pound body (fitted with "Society" 

 screw) can be substituted. A speciality 

 consists in the adjustment of the 

 mirror, which can be used as in Fig. 

 158 for transparent objects, or can be 

 brought above the stage as in Fig. 157 

 for opaque ones. 



Fig. 158. 



Gundlach's Globe Lens.* — This is a perfect sphere, consisting of 

 a hollow flint-glass globe, made in halves, and enclosing a solid 

 crown-glass globe. It is said to be constructed " according to a new 

 optical principle discovered by Gundlach. By this principle the 

 aberrations are corrected to a higher degree than has heretofore been 

 attained by any other construction. The lens has an optical axis in 

 any direction, hence the field is perfectly flat and distinct to the outer 

 edges ; and what is true of no other lens, the field is always the 

 largest possible." 



There are five sizes, 1, f, £, f , and \ inch. 



* 'Descriptive Price List of Gundlach's New and Improved Objectives,' 

 March 1882, p. 8. 



