PROCEEDINaS OF THE SOCIETY. 477 



fixing and removing objectives from the Microscope (supra, pp. 423 

 and 425). The latter was made upon the principle of the self-acting 

 chuck, there being three lateral jaws which were forced inwards as 

 the collar was turned. On each objective a ring was fixed in which 

 was a small groove, by means of which the attachment was made with 

 great facility. He had not yet had the opportunity of comparing this 

 appliance with others devised for similar purposes, but he knew that 

 it had been in the hands of a gentleman who was a very expert mani- 

 pulator, who said that it did all that was claimed for it. He had also 

 brought with him three objectives of American manufacture, which 

 might be of interest : one of these was a l-6th in. dry objective by 

 Spencer; another was a l-15th in. immersion, also by Spencer ; and 

 the third was a combination by Gundlach : it was a li in., but could 

 be converted into a 3 in. by simply removing the front lens. 



Mr. Ingpen asked if the camera lucida by Grrunow was claimed to 

 be new, or simply a convenient application of earlier methods. M. 

 Nachet, some years ago, produced a camera on the same reflecting 

 principle, but in which he used a film of gold so thin that it not only 

 reflected the drawing, but also allowed sufficient light to pass through 

 it to enable the object to be viewed. The plan was one which appeared 

 to work very well, the only disadvantage being that the object had to 

 be seen through a very thick piece of glass which in some cases 

 caused distortion of parts of the image. With regard to the nose- 

 piece, it seemed to him to work well, but it should be noted 

 that it would be necessary to have every objective intended to 

 be used with it, fitted with one of the grooved collars. Whether or 

 not it would prove better in practice then Mr. Nelson's nose-piece, 

 could only be determined by practical use. 



Mr. Curtis said that the " Facility " nose-piece appeared to be an 

 admirable contrivance, and one which certainly answered to its name. 

 Its action was perfect, provided care was taken to cut the ring 

 accurately. 



Mr. Hitchcock said, so far as Mr. Grunow was concerned, his 

 camera lucida was a perfectly original idea, but it was possible that 

 he had not the facilities for knowing what had been done elsewhere. 

 Indeed it would seem a little strange if so simple a contrivance had 

 not been thought of before. The rings were cut inside to the 

 Society's screw, so that any objective would fit them, and it was the 

 practice to send out four rings with each nose-piece. Of course if a 

 person had more than four objectives, he had only to order additional 

 rings for them. 



Dr. Anthony said that the weak point of Nachet's camera lucida 

 was that the image of the pencil could not be seen equally well over 

 the entire field, and that it became entirely lost towards the outer 

 side, or that which was farthest from the body of the instrument. 

 He would like to ask, therefore, if in this new arrangement the point 

 of the pencil could be more clearly seen. 



Mr. Crisp understood that it was claimed the pencil could be seen 

 with exceptional distinctness. 



Mr, Mayall drew upon the blackboard diagrams showing the con- 



