398 



OBITUARY. 



John Ware Stephenson. 

 Died 3rd May, 1901, aged 82. 



Mr. J. W. Stephenson, F.I.A., F.R.A.S., actuary to the Equitable Life 

 Assurance Society, was elected a Fellow of the Microscopical Society 

 of London in 1861, and was Treasurer of the Royal Microscopical 

 Society from 1872 to 1881. He contributed eighteen papers to the 

 Society,* among which the more important are: — (1) on an Erecting 

 Binocular 1 ; (2) on Bichromatic Vision' 2 ; (3) on a Polarizing Prism 3 ; 

 (4) on a Homogeneous Immersion Objective 4 ; (5) on a Catoptric 

 Immersion Illuminator 5 ; (6) An N.A. Table 6 ; (7) two papers on 

 mounting in dense media 7 . 



The first binocular Microscope was made in 1677, by Pere 

 Cherubin d'Orleans, Capucin, (Francois Laserre). The second bino- 

 cular was proposed by Sir Charles Wheatstone in 1851 ; he was unsuc- 

 cessful in persuading either Messrs. Ross, Powell, or Beck to construct 

 it. The third was invented (1851), constructed (1852), and published 

 (1853), by Professor J. L. Riddell of New-Orleans. t After this, 

 many forms of binocular Microscopes appeared, notably Wenham's 

 (1860), in the form as at present used. The binocular designed by 

 Stephenson in 1870, which is still known by his name, is similar 

 to that of Professor Riddell's, with the exception that the erecting 

 prisms in Stephenson's are placed immediately over the dividing 

 prisms instead of over the eye-pieces, as in Professor Riddell's. In 

 1872 Stephenson adapted his binocular to use with high powers, 

 by making the divided prisms smaller, and lowering them down 

 inside the mount close to the back lens of the objective ; and, further, 

 he made the erecting prism removable, so that a plate of black glass 

 could be inserted in its place, to act as an analyser for polarised 

 objects, the inclination of the body-tubes being at the proper polaris- 

 ing angle. The polarising and the high-power binoculars have not 

 come into general use, but the instrument in its original form has 

 been called by some of the most eminent microscopists of the day the 

 best instrument for mounting and dissecting as yet devised. In 1873 



* The titles of the various papers have been abridged. 



1 M.M.J., iv. (1870) p. 61, pi. 57; vii. (1872), p. 167, pi. 15; x. (1873) p. 41. 



2 Op. cit., vii. (1872) p. 215. 3 Op. cit., p. 246, fig. 1. 



4 J.R.M.S., i. (1878) p. 51 (woodcut). 5 Op. cit., ii. (1879) p. 36 (woodcut). 

 " Op. cit, p. 839. 7 Op. cit., iii. (1880) p. 564 ; ii. ser. 2 (1882) pp. 134 aud 163. 

 t Q.J.M.S., ii. (1854) p. 18, figs. 2 and 3. 



