31 



hardened they could break through the glass by a smart stab of the steel 

 point through the glass, and the hole could be chipped and filed out after- 

 wards. The only difficulty was in separating the glass from the metal 

 plate afterwards, great care being required to avoid breakage. There 

 was no difficulty at all in making the hole ; he believed he could do a 

 hundred of them in this way without breaking one. 



Mr T C. "White thought this plan was all very well for large holes, but 

 for small holes such as that required for this growing slide it would hardly 

 be available. 



Mr. Hailes did not think it would do for anything less than ^in., but it 

 would do quite as well for thin cover glass as for slides. He had, when 

 wanting to make a shallow cell, taken a fin. cover and broken a gin. hole 

 through it, thus producing a ring |in. wide in this manner without any diffi- 

 culty. 



Mr. Ingpen said that an important point in the use of Copal varnish 

 would be its refractive index, which he thought was a little lower than 

 Balsam. This might or might not be an advantage according to the objects 

 to be mounted. With diatoms, for instance, he thought there would be a 

 disadvantage, because the refractive index of the diatom silex was less 

 than that of Balsam, so that the use of Copal would in a greater degree 

 than Balsam tend to obliterate the markings. 



The Secretary said he had another little point of interest to bring before 

 them, namely, a series of lenses for dissecting purposes. They were 

 achromatic triplets, of particularly fine quality. Two sets had been sent 

 for the examination of members, one being mounted for dissecting and the 

 other for the pocket. They were approximately Hin., lin., fin., |in., and 

 fin. ; their definition was extremely fine, and their flatness of field very 

 great. They were manufactured by Steinheil, and were lent for exhibition 

 by Messrs Murray and Heath, Steinheil's London agents, from whom par- 

 ticulars as to price, &c., could be obtained on application. 



Mr. Geo. Hind then read a paper " On Collecting and Mounting Spiders' 

 webs for the Microscope." 



Mr. T. C. White said that he had listened with much pleasure to Mr. 

 Hind's paper — it reminded him of a plan which he had often adopted in 

 mounting insects caught in spiders* webs. He cemented a cell upon a glass 

 slide, and having coated the edge of it with balsam, brought it into contact 

 with the web, so that the capture was suspended in the middle of the cell ; 

 another cell was then placed upon the top of the first one, and the cover- 

 ing glass put on in the usual way. 



Mr. Hailes said there was one point in Mr. Hind's paper, to which, 

 for the sake of being accurate, he thought he might call attention. It re- 

 ferred to the large spiders catching birds. This was a story which had 

 been repeated over and over again, but it was one which rested entirely on 

 the statements of Mdlle. Merian, which, so far as he was aware, had never 

 been confirmed. He had the opportunity some time ago of seeing Mdlle. 

 Merian's work, and he noticed the careful way in which she expressed her- 

 self. In the case of her own observation she always says " I have seen " 



