INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 1067 



carriage P running therein, and carrying a condensing-lens and other 

 accessories, either singly or combined, substantially as shown and 

 described. 



3. A turning-holder I, carrying an index M, in combination with 

 a graduated arc i, and a clamping device, to secure the holder either 

 in the radius of the track D or at any degree of obliquity in which it 

 may be placed, to carry an achromatic illuminator or other accessory, 

 substantially as shown and described. 



4. The combination of a convex lens L, of piano-spherical or suit- 

 able form, with a plano-concave lens a, of counterpart curvature, and 

 a carriage P carrying said concave lens, and also an illumination- 

 tube, substantially as shown and described. 



5. The combination of a convex lens L, and an arm n, on the 

 axial end of which said lens is mounted, with a circular track D, and 

 carriage P, carrying a suitable illumination device, substantially as 

 shown and described. 



6. The combination of a graduated circular track D, and carriage P, 

 for guiding and supporting an illumination device and other acces- 

 sories, with a stage S for supporting the object-slide, substantially as 

 shown and described. 



In witness whereof I have hereunto subscribed my name. 



Egbert B. Tolles. 

 In presence of — 



P. S. Yendell, 

 Abthub MoNally. 



Bulloch's Sector Microscope.— The next in order of date is the 

 Microscope shown in Fig. 133, which was designed by Mr. W. H. 

 Bulloch, of Chicago, U.S.A., and exhibited in 1873. 



Tlie figure shows the general design of the Microscope. The 

 substage was described by Mr. Bulloch as follows : " Compound 

 substage, with the most complete movements for centering or for 

 oblique light, with achromatic condenser, has one-fourth inch move- 

 ment each way, rack and i)inion vertical movement, rack and pinion 

 movement in arc of circle for oblique liijht. . . ." 



The sectoral arc is shown in the figure just below the stage, as well 

 as the rack and milled head of the pinion by which the substage is 

 moved. The mirror is on a separate bar and can bo swung above the 

 stage and clamped by a screw, the milled head of which is seen at the 

 back of the instrument. 



Zentmayer's Centennial and Histological Microscopes. — 

 (1) Ccntennidl. — This ^Microscope, sliown in Fig. l.'U, waslirst exhibited 

 at the Academy of Natural Sciences of I'hiliidelpliia on April 2, 187G • 

 and then at the Phihul.'lphia Centennial Exliibition in 187(5, and sub- 

 se([Uontly at tho Paris Fxhil)ition in 1878. 



The following is j\[r. Zoiitinayer's de.seription of it.* " Tho instru- 

 ment is I'J inches high when arranged for use. It is mounted on a 



* 'IlluHtratrd Prioo Lisl.' 4tli c<Ht. 



