( 660 ) 

 PROCEEDINaS OF THE SOCIETY. 



Meeting of 11th June, 1884, at King's College, Steand, W.C, 

 THE President (the Eev. W. H. Dallingbr, F.E.S.) in the 

 Chair. 



The Minutes of the special and ordinary meetings of 14th May- 

 last were read and confirmed, and were signed by the President. 



The List of Donations (exclusive of exchanges and reprints) re- 

 ceived since the last meeting was submitted, and the thanks of the 



Society given to the donors. 



•^ ^ From 



Heurck, H. van. — Synopsis des Diatomees de Belgique — Table 



Alphabetique. 120 pp. 8 vo, An vers, 1884 The Author. 



James, J. B. — Aids to Practical Physiology, viii and 24 pp. 



8vo, London, 1884 Mr. Williams. 



Mr. Crisp called attention to the extraordinary character of the 

 latter book, and read extracts from it (supra, p. 629). 



Mr. Crisp described Prof. Zenger's method of constructing 

 " Endomersion " objectives by using a mixture of ethereal and fatty 

 oils, which he claimed enabled the chromatic aberrations to be much 

 more effectively dealt with (supra, p. 616). He exhibited an objective 

 sent by Prof. Zenger. 



Mr. J. Mayall, jun., in reply to Mr. Crisp, said that he had 

 examined the objective exhibited, and found that it was not a 1/50 in., 

 as claimed, but in truth not more than 1/8 in. He also found that 

 the spherical aberration was very imperfectly corrected. 



Dr. Wallich briefly described his new condenser, which he ex- 

 hibited in operation at the close of the meeting. 



Mr. B. Piffard's new slide was exhibited and described by Mr. 

 Crisp (supra, p. 655). 



Mr. J. Mayall, jun., exhibited and described a simple mode of 

 applying amplifiers to a Microscope (supra, p. 607). Several methods 

 had been devised, and the one by ToUes was no doubt very good, but 

 it was expensive. For the form which he now showed he did not claim 

 any originality, because he remembered to have seen the same plan 

 adopted, though in scarcely so simple a manner. His was simply a 

 slide with three concave lenses, which could be pushed through the 

 tube of the Microscope, so that either could be used as required. By 

 this means the working distance could be increased by 75 per cent. 

 The one to which he had referred had a rotating disk, and he thought 



