268 PEOCEEDINGS OF THE SOCIETY. 



lamp, so that when once they had heen accurately centred, they could 

 be moved along the rail to any required position without getting out of 

 the centre. 



The first portion of the exhibition was intended to illustrate the use 

 of the arrangements for projecting the images of opaque objects upon the 

 screen ; such objects as coins, post-cards, &c, being jwwerfully illumi- 

 nated by a beam of light reflected upon them by a mirror, and shown 

 upon a small screen placed in the middle of the room at a distance of 

 about 15 feet. This was followed by the exhibition, on a larger screen 

 at a greater distance, of a large number of microscopic slides, comprising 

 insects, plant sections, marine polyps, and preparations of animal tissues, 

 chiefly by means of Messrs. Zeiss's micro-planar objectives. 



As showing the capabilities of the apparatus to^exhibit ordinary 

 lantern slides, the last portion of the exhibition consisted of a number 

 of views of landscapes, plants, and animals, as well as some extremely 

 line photomicrographs of diatoms, &c, which had been lent for the 

 occasion by Dr. Spitta. 



The whole of the apparatus is constructed so as to render this 

 transition from micro- to macro-projection, and the reverse, very rapid 

 and easy, all the requisite rearrangement of parts being readily effected 

 in one or two, or at the most in three minutes. 



The President, in inviting remarks from those present, said he 

 thought it was obvious that they had before them an instrument which 

 must be of great utility in illustrating public lectures, by showing the 

 minute details of sections on a large scale, much larger than they had 

 the conveniences for doing in that room. He was sure that all present 

 would join him in giving their best thanks to Dr. Measures for this 

 very interesting and instructive exhibition. 



Mr. Lewis Wright said he had heard a great deal as to the excellence 

 of Messrs. Zeiss's micro-planars, and he had long desired to see what 

 could be done with them. He would only say now that what he had 

 seen that evening fully came up to anything he had anticipated ; their 

 flatness of field and the quality of the definition up to the margin of tho 

 field were remarkably good. The highest power, however, which seeiucd 

 to have been used was the 20 millimetre, whereas he should very much 

 like to have seen something with a 1/2 iuch, though he had been very 

 pleased with what had been shown. 



A vote of thanks to Dr. Measures was then put to the Meeting and 

 carried unanimously. 



The following Instrument was exhibited:— 



Mr. E. M. Nelson : — A " Jones' Most Improved combined Micruscope 

 and Apparatus." 



New Fellows: — The following gentlemen were elected Ordinary 

 Fellows of the Society:— Mr. Konald Hamlyn-Harris, Major Francis 

 Kobert Winn Sampson. 



