578 PROCEEDINGS OF THE SOCIETY. 



Mr. Crisp exhibited a mirror made by the Bausch and Lomb 

 OiHical Company, to which was fitted a diaphragm with an oblong 

 slit (supra, p. 523). 



Mr. J. Mayall, juu., said that the principle of having a diaphragm 

 over the mirror was applied by Dellcbarrc in the last century, and 

 had been subsequently repeated. He remembered having seen 

 Dr. Charles Robin use similar diaphragms, which he found very 

 useful. 



Mr. Crisp mentioned that a short time ago a traveller in Asia 

 gave an account of his discovery of the "wax insects," but stated ho 

 had no means of examining them otherwise than with the naked eye. 

 This had led liim to look up the account of Gray's water Microscopes, 

 in order to call attention to the very simjjle means by which magni- 

 fying power might be obtained under the circumstances in which this 

 traveller found himself placed. Even a drop of water on a piece of 

 glass would have furnished the power required. Mr. Mayall had 

 constructed a model of Gray's apparatus, which he would describe. 



Mr. J. Mayall, jun., said that Gray had described his process 

 very clearly. He employed a plate of metal 1/16 in. thick with 

 a hole drilled through it about 1/30 in. in diameter, one side of 

 which was countersunk to 1/8 in. in diameter, and the other side to 

 about half that extent. A droj) of water was then put in each of the 

 countersunk spaces, and it was quite surprising how much magnifying 

 power was obtained, and how clearly the object was shown. Gray 

 suggested that a little cavity should be made in the support in which 

 to put a drop of water containing organisms for examination, but this 

 was not quite so successful. It was not necessary to employ metal 

 for the purpose, a piece of cardboard or wood answered perfectly. 

 Gray's object was to make a simple as well as an effective apparatus, 

 and in this he had been quite successful, and when an observer found 

 himself without a lens he could not do better than follow the 

 suggestion. Gray found it preferable to use a solution of isinglass, 

 which would remain where it was placed better than water. 



Mr. Beck said that, some years ago, before the race of street 

 " patterers " became extinct, there used to be a man who went about 

 selling Microscopes made somewhat on this plan, but the lens was 

 made of a drop of Canada balsam. 



Mr. Mayall said that, in addition to Canada balsam, there were 

 other substances such as castor oil, and, in fact, many of the highly 

 dispersive oils which would give even better results. 



Dr. Maddox read his paper, " An Experiment on Feeding some 

 Insects with the Curved or ' Comma ' Bacillus and also with another 

 Bacillus {Bad. suhtilis)," illustrating the subject by preparations ex- 

 hibited under the Microscope. 



Mr. Cheshire said that he must, in the first place, congratulate 

 Dr. Maddox on the time he had been able to keep his bees alive in a 

 state of isolation ; they were not at all easy to keep so under ordinary 



