PROCEEDINGS OF THE SOCIETY. 107 



a glut of these instruments. As to this new one of Hofmann's, he 

 could not see what the si^ecial advantage of it was. In the first place 

 they had to take out the eye-piece because the reflecting surface was 

 so far from it that they could not get any vision with it in its place. 

 This he thought was a great disadvantage. Then, again, how was it 

 proposed to see the pencil point ? The rays were thrown on a piece of 

 glass (A), (see Fig. 2, p. 21), and reflected to (B), and from that were 

 reflected through the aperture (E). The observer at (E) looked 

 through a piece of plate glass with two surfaces, and somewhere on 

 the ground — upon the scale on which the drawing was made — he 

 would see the object. If they did not mind the loss of light, they 

 could get all the advantages claimed, by simply making a hollow 

 Wollaston's camera ; but in both cases they had the disadvantages of 

 looking through two surfaces of glass, and a great loss of light. With 

 all the changes which had been made at different times, he still 

 believed that if persons would be careful to split the ray by looking 

 with half the pupil only, and would also take the trouble to properly 

 modify the light, there was nothing better than the old form. 



Dr. Hudson said that as one who very frequently drew objects from 

 the Microscope, he could only say that for such drawings as his of 

 living objects the camera lucida was nearly useless. The method he 

 adopted was to have a piece of glass ruled in squares, which covered 

 the field of view ; and, having ruled paper always at hand, the object 

 was drawn square by square : and even the most active rotifer would 

 sometimes remain quiet long enough to get the outline correctly. With 

 an inanimate object he could not conceive anything more easy than 

 this method, even to an indifferent draughtsman. 



Mr. Ingpen said that Hofmann's camera appeared to be identical 

 with one by Amici, which was forty years old at least. If the piece 

 of glass (B) were extended, it would be the same exactly. 



Mr, Crisp said it was only within the last few months that 

 Dr. Hofmann had removed part of the plate of glass (B), the restitution 

 of which would make the camera the same as Amici's, according to 

 Mr. Ingpen's statement. In the drawing of this non-microscopic form, 

 which appeared lately in 'Nature,' it was shown according to its 

 original design. 



Mr. Stewart read a Note by Mr. A. D. Michael with reference to 

 the finding of the male of Cheyletus veniistissimus (see vol. i. p. 317). 



Mr, Crisp called attention to the remarks of Professor Adams at 

 the meeting of the Physical Society, on 9 th November, on the advan- 

 tages possessed by a portable form of Dietzl's diffraction ajiparatus 

 when used as a polarizer for the Microscope (see p. 87). 



Mr. Ingpen made some remarks upon the ^-inch objective exhibited 

 by Mr. Crisp at the October meeting,* made by the Bausch and Lomb 



' Journal,' vol. i. p. 312. 



