564 



by the Drone Fly {Erisialis tenax), and on its hovering habit, 

 was read by the Secretary, six slides and some photographs 

 of the specimens being exhibited in illustration. 



Mr. Wesche thought the Club was to be congratulated on 

 acquiring the slides which Mr. Harris had so kindly presented. 

 It was well known, however, that the sound referred to was 

 produced not by the wings, but by the spiracles. 



A vote of thanks was then unanimously voted to Mr. Harris 

 for his paper. 



On the motion of the Chairman a vote of thanks was also 

 given to Mr. Curties for the loan of microscopes under which 

 were shown the slides presented by Mr. Harris. 



Notices of meetings, etc., for the ensuing month were then 

 given out, and the proceedings terminated with the usual 

 conversazione. 



May 15th, 1903. — Ordinary Meeting. 



J. G. Waller, Esq., F.S.A., Vice-President, in the Chair. 



The minutes of the meeting of April 17th, 1903, were read 

 and confirmed. 



The following gentlemen were balloted for and duly elected 

 members of the Club : Mr. George H. Gabb, Lieutenant- Colonel 

 G. L. Tupman, and Mr. A. H. W. Cleave. 



The additions to the Library were announced, and the thanks 

 of the Club voted to the donors. 



Mr. C. L. Curties said he had brought for exhibition an 

 apparatus made upon the lines of Dr. Spitta's method of 

 obtaining pure monochromatic light. It consisted of a Nernst 

 lamp, with an aplanatic condenser, and a grating fitted upon 

 a prism so as to give a direct beam of light to the microscope 

 and a moderate-sized spectrum sufficient to fill the whole field 

 of a 2 -inch objective with one colour only. He had hoped to be 

 able to exhibit this in action, so that members might see what 

 could be done with monochromatic light obtained in this way. 

 Unfortunately, however, through some defect in the lamp, he 

 was unable to show this, but hoped to be able to do so on a 

 future occasion. 



