538 SUMMARY OF CURRENT RESEARCHES RELATING TO 



under the conditions specified: (l) Those showing absorption bands, 



by these new tools, and when I received them I found, to rny astonish- 

 ment, that they would enter none of the eight Microscopes I had. The 

 experience of others w 7 as similar, and as representations were frequently 

 made to the Royal Microscopical Society upon the subject, the Council, 

 in 1*90, appointed another sub-committee to report upon the whole 

 question. This sub-committee, of which I had the honour of being a 

 member, found that the tap which had been copied was a very badly- 

 cut screw, which, when tested by the Society's standard gauges, was not 

 of the Society's standard size. We ordered that it and its copies should 

 be destroyed. We recommended that new sizing-tools should be made 

 in accordance with our standard gauges, and we suggested that limiting 

 gauges should be added to our standards. Our recommendations * were 

 adopted by the Council, and the new gauges and sizing tools were 

 ordered from Messrs. Whitworth. These were supplied, and, so far as 

 these sizing-gauges are concerned, I personally tested every one, and I 

 am quite sure that all objectives and nose-pieces sized by any one of 

 those will be interchangeable. I purchased a set (now on the table as 

 I write). The legend on it is " R.Mic.So., London, 1897. Whitworth, 

 Manchester, .8015 36ths," and on the die is .7967. 



Mr. T. Powell, also a member of the sub-committee, exhibited the 

 original sizing-tool his father had bought. He said it was the one he had 

 always used. After all these years it was in as good a condition as it was 

 when new ; it was made and hardened in one piece, and was without the 

 three adjustable blocks which are fitted to the new dies. 



The Continental manufacturers to whom the Society had supplied the 

 wrong screw were very indignant, and rightly, too. At first they re- 

 fused to accept the new tools, but after Mr. C. Beck had pointed out to them 

 the confusion that must inevitably arise, they chivalrously waived the 

 matter, and adopted the true standard screw. Mr. C. Beck deserves the 

 warmest thanks of all microscopists for his good offices in this matter. 



So far as my own experience goes, I have not seen a single objective 

 that has been sized by these new tools that is not interchangeable. If 

 a new standard, or any alteration in the Society's present standard, is pro- 

 posed to the Continental manufacturers, I think, after what has already 

 occurred, there will be some difficulty in persuading them to accept the 

 change. 



Personally, I prefer an objective that screws very loosely into a nose- 

 piece, and fixes into position by facing up on its flanges ; so, looking at 

 the question from every point of view, my counsel would be to leave 

 things as they are. " 



(3) Illuminating- and other Apparatus. 



Directions for using Glass Micrometers. — Messrs. Carl Zeiss have 

 published, under the above title, a very clear and complete pamphlet of 

 8 pages, dealing with microscopic magnifications. Eye-piece micrometers, 

 Plagge projection micrometer eye-pieces, stage-micrometers, and methods 

 of determining magnifying powers, are all dealt with. 



* See this Journal, 1896, p. 389. 



