Dr. Joule on the Thermal Effects of Compressing Fluids. 365 



I 



December 9. — Sir Benjamin Collins Brodie, Bart., President, in the 

 Chair. 



The following communications were read : — 



" Researches into the Nature of the Involuntary Muscular Tissue 

 of the Urinary Bladder." By George Viuer Ellis, Professor of Ana- 

 tomy in University College, London. 



" On the Ova and Pseudova of Insects." By John Lubbock, Esq., 

 F.R.S., F.L.S., F.G.S. 



December 16. — Sir Benjamin C. Brodie, Bart., President, in the 

 Chair. 



The following communications were read : — 



Extract of a Letter from Professor Lament to Major-General 

 Sabine, Treas. and V.P.R.S., dated Munich, Dec. 19, 1858. 



"My magnetic observations in France, Spain, and Portugal are 

 now published, and a copy for you is on the waj-. The observations 

 of last summer are under the press. They comprehend about thirty 

 stations in the North of Germany, Belgium, Holland, and Denmark. 

 Next year I am going to Italy, and in 18G0 I intend to revisit 

 Spain, in order to observe the total eclipse of the sun, and also 

 to make magnetic observations. 



" I have found that on the Continent the lines of horizontal intensity 

 move from south-west to north-east, making an angle of about 20° with 

 the meridian, that is, in a direction coinciding with the lines of de- 

 clination. The lines of inclination seem to move in the same direc- 

 tion, and the motion of the lines of declination will probably coincide 

 with the lines of horizontal intensity. Calling -f^H and — Ai the 

 annual changes of horizontal intensity and inclination of a central 

 station (suppose London), the animal changes for a place situated x 

 degrees in latitude to the north, and y degrees in longitude to the 

 west, will be — 



All —0-000 18a; -|-000008y (absolute measure, French units), 

 — Ai +0'-21a: — 0'-09y. 



" Tlie new survey of tlic British Islands will offer an o]tportuiiity of 

 testing the correctness of these ibnnulsc." 



