ADJOUKNED DISCUSSION IN LONDON 237 



The evidence of the work is on record, both in the Journal of 

 the British Science Guild and the Royal Microscopical Society, and I 

 fancy that the manufacture of both instruments exhibited to-night 

 were to some extent influenced by the specifications prepared by 

 the Committee. 



Mr. Conrad Beck said that the standard instrument made by 

 his firm was made to the specification of the British Science Guild 

 Committee, but the larger one, made by Messrs. Swift, was quite a 

 different matter. The latter was more of a special research type. 

 He certainly welcomed the suggestion that a small sum of money 

 should be put up to assist in manufacturing microscopes. But what 

 was meant by a small sum ? In some instances upwards of £20,000' 

 had been spent in tools and machinery; Messrs. Watson and his 

 own firm had each expended an enormous amount of money on 

 machinery and tools which it was hoped in course of time would be- 

 found advantageous to microscopical work, and if a small sum meant 

 something of this nature it was an excellent proposition. 



Mr. Watson Baker : The microscope which our firm has made 

 according to the specification of the British Science Guild is not 

 here to-night, but I am glad to take this opportunity of saying 

 that we should welcome any members of the Royal Microscopical 

 Society to our works to see exactly what is being done. 



I believe that Col. Clibborn himself would be pleased to see 

 that microscopes are being made by machinery in a manner not 

 hitherto done in this country. It has taken us 12 months to put 

 up a new building and make the necessaiy tools, but we have accom- 

 plished it, and if British users could be induced to visit us and 

 se© what we have done and what it has involved, we should be very- 

 pleased. 



Mr. Perkins : I was struck by the remark of Professor Desch in 

 his paper when he said that microscopes wear because of the bad 

 material of racks and pinions. I have found in a fairly long ex- 

 perience of microscope repair that sometimes the German slides are 

 softer than the English slides, so that does not, in my opinion^ 

 account for the fact that the English microscope wears quicker than 

 the German. It has always seemed to me that the English makers, 

 in spite of their undoubted ability, overlook the fact that if you 

 want to reduce wear on the slides of a microscope, they must bear 

 properly upon each other. It is no good putting in slides which 

 bear at points, as in Fig. 1. Wear very quickly takes place at those 

 points and develops a shake, and you get a loss of stability, such 

 as Professor Barnard spoke of. The closest analogy I can put forward 

 is an ordinary bearing. If, for argument's sake, the inner bearing 

 is much smaller than the outer (Fig. 2), you get point metal to 

 metal contact and quick wear. If, however, it fits as in Fig. 3, 

 the lubricant stops in in an unbroken film, and you get long and 

 efficient wear. I have seen microscopes 20 years old which have no 

 shake in them and still fit perfectly all over. Then, again, the 

 weakness of design of the usual spring fitting is another point which 



