Popular Science Lectures. 207 



combine to attract moths and other insects. Brilliant 

 yellows, reds, and blues, are essentially diurnal, and 

 almost universally scentless, because the colour alone is 

 sufficiently attractive. Dull and lurid colours are often 

 associated with heavy disagreeable odours, for the pur- 

 pose of attracting flies. 



The lecturer then proceeded to explain a few of the 

 contrivances by which orchids and other flowers are fer- 

 tilised, showing some of the insects which carry on the 

 work, and their manner of procedure. 



The leclure was illustrated by a few diagrams and 

 a large number of different flowers, many of which 

 were continually referred to for the purpose of explain- 

 ing the various points in the leclure. 



14. — "photography: its nature, history and application. 



Delivered on Tuesday, June 25th, by H. H. Cunningham, B.A., 

 Stipendiary Magistrate of British Guiana. 



The lecturer began by explaining the essentially sim- 

 ple principle of photographic processes generally ; and 

 gave a detailed historical account of the building up of 

 the art and science of photography, with special refer- 

 ence to sensitive plates, and the methods of fixation of 

 the images — the various prominent investigators being 

 named, and the substances made use of described. The 

 special applications of modern photography were then 

 briefly indicated : such as for portrait and pictorial pur- 

 poses and the reproduction and multiplication of maps, 

 plans, manuscripts, and drawings ; for astronomical, 

 microscopical, and geological matters ; for the registra- 



