145 



to be employed, and he hoped to receive the opinions of the members npon 

 this and other matters ; bnt at present he used an ordinary low-power achro- 

 matic objective, made so as to slip into the arm without screwing; there 

 was great convenience in thus mounting and using a simple lens. With the 

 old doublet there was much difficulty in working comfortably, and whether 

 a person could do so or not depended a good deal upon his nose, being 

 specially troublesome in the case of those persons who had somewhat aspir- 

 ing noses. In addition to the lens which he had placed upon the instrument, 

 there was another belonging to it of half the focal length. Now, supposing 

 they had made their dissection successfully, the point was how to be able to 

 convert the instrument at once into a compound microscope without disturb- 

 ing either the lens or the object. One of his aims in life had been to get 

 microscope makers to abolish screws, which he regarded altogether as 

 abominable inventions, and in this instance, the compound body had been 

 made to slip over the outside of the socket in which the objective had been 

 placed. This plan answered fairly well, but he thought it would be better 

 to have it made to fit rather more easily, and to be secured by a bayonet 

 joint, because, supposing that the power employed was not sufficient for the 

 purpose, then inconvenience arose unless the body could be got off again 

 with sufficient ease to ensure the object remaining undisturbed by any jerk 

 or movement. With the improvement of the bayonet joint, it would be 

 easy to remove the body, and having taken out the first lens and dropped 

 jn, say a one-eighth in., the body would go on again without any disturb- 

 ance. He had the instrument before them made upon that pattern, to see 

 how the thing would work ; he had used it for the past six or eight months 

 incessantly, and could certainly say that for his requirements it was the 

 best thing he had seen, and he believed that with the little addition of a 

 bayonet joint it would be as nearly perfect as any instrument of the kind 

 could well be. He thought that all persons who had been occupied in mak- 

 ing minute dissections would see that it had value, and met all the require- 

 ments of the most delicate work. He hoped that the members would 

 examine and criticise it, and make any suggestions that occurred to them 

 for its further improvement, for it was becoming of very great importance 

 to examine thin sections and minute portions of dissections without sub- 

 jecting them to any such disturbance as to cause the slightest alteration, 

 and it was equally important to be able to bring to bear upon them under 

 such conditions the highest powers that might be needed. 



Dr. Matthews enquired if the President spoke of dissecting in water ? 



The President said that he referred to dissection in a very shallow trough, 

 and by transmitted light. 



Mr. Ingpen was sure that the members would feel highly indebted to 

 their President for bringing this instrument before them. The question of 

 dissecting microscopes had always been a difficult one, from the different 

 requirements of various individuals, and in many cases there was too great 

 a desire for cheapness. He added some remarks upon the best form of slow 

 motion, and on the objectives most suitable for the purpose, and then called 

 attention to a number of dissecting microscopes which had been in use at 



