XXVUl CONTENTS 



PAGE 



Ideal Series of Objectives for Microscopical Work .. . . Part 4 679 



High Amplifications „ 679 



Conditions of Microstereoscopic Vision — " Penetration " . . „ 680 



Abbe's Stereoscopic Eye-piece ,, 689 



Illumination for Binocular Microscopes with High Powers. 



{Figs. \m and 1Q\) „ 690 



" Working Distance and its relations to Focal Length and 



Aperture " „ 692 



Invention of the Binocular Microscope , 693 



Priority of Invention „ 693 



Beck's'' Ideal" Microscope. {Fig.lQQ) Part 5 805 



Cosson^s " Dissecting " and " Observing " Microscope. 



(^Fig. 167) , 807 



Holmes's Class Microscope. (^ Fig. 16S) „ 808 



Pocket Microscope. (Figs. 169 a7id 170) „ 809 



Swift's " Challenge" Binocular Microscope (C). {Fig. 171) „ 810 

 Verick's " Goniometrical Microscope for Mineralogy'' 



(Figs. 172-174:) , 812 



Seibert and Kraft's Dissecting Microscope. (Figs.n5andl76) „ 814 



The Battle of the Stands. (Fig. 177) „ 815 



Fine Adjustment by the Eye-piece. (Fig. 178) . . . . „ 816 



Zeiss' s Camera Lucida with Two Prisms. (Figs. 179 and ISO) „ 818 

 Silver Films for Instruments of the Camera Lucida Class. 



(Figs. 181-183) „ 819 



Apparatus for Examining Diffraction Spectra „ 822 



Sorby's Binocular Spectroscope. (Figs. 181 and 185) .. „ 822 

 Ease's Zoophyte Trough, Live-Box, or Growing Slide. 



(Figs. 18Q and -187) , 824 



Malassez's Moist Chamber „ 825 



Mackenzie's Swinging Substage. (Fig. 188) ,, 825 



Swiff s Eadial Traversing Substage Hluminator. (Fig. 189) „ 827 

 Kelner Eye-piece and Equilateral Prism as a Means of Illu- 

 mination. (Figs. 190-192) „ 828 



Difference in the Appreciation of the Apparent Size of 



Microscopical Images by different Observers 829 



Conditions of Aplanatism for Wide-angled Pencils. 



(Fig. 193) „ 831 



Penetrating Power of Objectives „ 831 



Penetration , 833 



Advantage of the Binocular „ 835 



Braham's Lamp „ 854 



Descriptions of New Microscopes Part 932 



Lacaze-Duthiers' Aquarium Microscope. (Figs.203 and 201) „ 932 



Nachet's Petrographical Microscope. (Figs. 205 and 206) „ 934 



Miller's Microscope with Telescopic Eye-piece „ 935 



Salt's Pocket Microscope (Swift-Brown Pocket Microscope). 



(Figs. 207-209) „ 936 



Sidle' s '' Acme" Lithological Microscope. (Fig. 210) .. „ 937 



Browning's Platyscopic Lenses „ 939 



Nachet's Porte-loupe. (Fig. 211) „ 939 



Lacazc-Duthiers' Portc-loupc. (Fig. 212) „ 939 



