QUARTERLY JOURNAL 



OF 



MICROSCOPICAL SCIENCE. 



ORIGINAL COMMUNICATIONS. 



On the Enlargement and Multiplication of the Images of 

 Objects, xohen viewed hy the Light admitted through small 

 Apertures ; and on the Diascope, a new Optical Instrument. 

 By John Gorham, M.R.C.S.L., &c. 



{Qontinued from Vol. II., page 234.) 



It has been before noticed that less attention has been 

 bestowed upon the investigation of objects that lie near at 

 hand, within an inch or two, we will suppose, of the eye, than 

 upon objects which are placed at a considerable distance from 

 it, that, for example, of as many furlongs. I have also endea- 

 voured to show that small circular perforations made in a 

 card, and rendered semi-transparent, constituted in themselves 

 objects well adapted to illustrate the magnifying power of short 

 spaces, by presenting a rapid and palpable enlargement of 

 the visual angle to the eye ; and, lastly, a series of phenomena 

 has been described, which resulted from viewing small figures 

 held close to the eye in front of such apertures, and rendered 

 visible by the light admitted through them. 



The whole subject arranges itself therefore under two dis- 

 tinct divisions, which comprise : — 1. An examination of the 

 images formed by viewing objects held in front of small aper- 

 tures ; and 2. An examination of those images which result 

 from placing the objects behind the apertures. 



1. Of images formed when the eye and the object are both 

 on the same side, that is, in front of the apertures. 



We have already seen that when bodies not exceeding the 

 diameter of the pupillary opening of the eye are held in close 

 proximity to the visual organ, and are then examined by the 

 light admitted through small inlets about the fortieth of an 

 inch in diameter, their images become magnified, multiplied, 

 and inverted; and further, that they are illuminated with light 



VOL. ITI. B 



