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as he had stated, " for general purposes." Mr. Williams's machine, he 

 considered, was almost perfect for soft substances. He thought himself 

 perfectly justified in adopting some of Dr. Hoggan's ideas, and improving 

 upon them, for Dr. Hoggan came there and threw down the challenge to 

 any one to improve upon his model if he could. Dr. Hoggan's machine 

 was necessarily expensive, from the way in which it was required to be 

 made, bat his own was quite of simple construction, in being made of tubes 

 sliding into one another, and such tubes could be got ready-made anywhere. 

 Dr. Hoggan's machine had the same defect as most others — that of packing 

 the substances tightly into a tube, and then forcing them forward by jerks. 



Mr. Ingpen exhibited to the meeting an ingenious contrivance by Mr. 

 Swift for giving a final and perfect correction to the centering of an objec- 

 tive. It was a small adapter screwed into the body of the microscope, into 

 which the objective was screwed as into the ordinary nose-piece. This 

 little apparatus had two small screws, giving a lateral motion in two 

 directions, by means of which perfect centricity might be attained. All 

 persons who used high powers must have been troubled by the difficulties 

 they met with in getting accurate adjustments, and this little piece of 

 mechanism supplied them with what they needed — means of final adjust- 

 ment of the optic axis. 



Mr. B. T. Lowne addressed the meeting " On the Application of the 

 Microscope to Physical and Physiological Research." He said he was 

 sorry to come before them in one sense as a defaulter, for he had intended 

 to exhibit a piece of apparatus which he had adapted to his microscope, and 

 which, to a certain extent, might be said to mark an epoch in Microscopic 

 Science. Unfortunately, however, in packing it up to bring it to the 

 meeting, he happened to break it ; but although unable to show it on that 

 occasion, he hoped to do so at the Soiree, together with some other things 

 of much interest. The microscope was, as they were all well aware, an 

 instrument admirably adapted for measuring minute objects and minute 

 spaces, but it had only quite recently been used to measure minute varia- 

 tions of force. In the application to which he had referred it was used to 

 measure very small quantities of electrical force. The apparatus was made 

 by Lippmann in Germany, and although it had been in use there for four or 

 five years, it was quite unknown to English Physicists, until it was brought 

 under their notice by means of the Loan Collection of Scientific Instruments 

 at South Kensington. It was called an electrometer, and its most delicate 

 portion consisted of a glass tube drawn out to an extremely small capillary 

 tubular point at one end, the bore of which should not exceed the jlj, in., 

 and if it were as small as the 3 j S , it would be better still, and it was this 

 small extremity which he had the misfortune to break before coming to the 

 meeting. Mr. Lowne then, by means of a diagram drawn upon the black 

 board, described the apparatus as consisting of the glass tube (described 

 above), A, the tapering extremity of which passed into a vessel (B), and the 

 other end was attached to a metal vessel (C) by means of a piece of india- 

 rubber tubing (D). The tube (A) was then filled with mercury, which could 

 be forced up the taper end, or allowed to run back by turning the screw (E) 



