for the year 1871. xxxvii 



frequency and number of sun spots, had induced me to 

 compare the periods of magnetic disturbances and auroras 

 with the prevailing weather. 



At the March meeting I described a new form of automatic 

 spectroscope which I had devised some ten months pre- 

 viously. The arrangement provided that a train of prisms 

 should be adjusted to the position of minimum deviation by 

 the act of pointing the observing telescope to any required 

 portion of the spectrum. Mr. MacGeorge also made some 

 notes on " Observations with the Great Melbourne 

 Telescope," in which he pointed out that still further changes 

 had taken place in the nebula of Eta Argus since Mr. 

 Le Sueur's last observations. 



Mr. G. Foord contributed a very interesting paper at the- 

 April meeting on the " Fluid Contents of Enhydros," in 

 which he gave the results of an analysis of the liquid con- 

 tained in these strange productions, as well as a description 

 of the microscopic appearances of the inner and outer 

 surfaces of the walls of the cavities, suggesting a theory of 

 their formation. 



At the May meeting, Professor Wilson called the attention 

 of the members to the total eclipse which would be visible in 

 the northern part of Australia in December next, and 

 suggested the propriety of an endeavour on the part of the 

 Society to organise an expedition to observe it, and a 

 committee was appointed to carry this suggestion into 

 effect. At the same meeting Mr. A. K. Smith described and 

 illustrated a new hydrostatic chain and clock weight. 



Three papers were read at our June meeting — one by 

 myself, on Gun Cotton, in which I described the various 

 kinds of gun cotton, their properties, methods of use, as well 

 as the results of some experiments I had made with the 

 material ; Mr. White read a paper on " Improvement of the 

 Mariner's Compass," in which he recommended the abandon 



