Monday, I7th April 1854. 



Page 



Notice of the Completion of the Time-Ball Apparatus. By 



Professor C. Piazzi Smyth, .... 238 

 On the Mechanical Energies of the Solar System. By Profes- 

 sor William Thomson, . . . .241 



Monday, 1st May 1854. 



On the Action of the Halogen Compounds of Ethyl and Amyl 

 on some Vegetable Alkaloids. By Henry How, Assistant 

 to Professor Anderson of Glasgow, . . . . 244 



On the Mechanical Value of a Cuhic Mile of Sunlight, and on 

 the possible density of the Luminiferous Medium. By 

 Professor W. Thomson. ..... 253 



Account of Experimental Investigations to answer questions ori- 

 ginating in the Mechanical Theory of Thermo-Electric 

 Currents. By Professor W. Thomson, • . . 255 



Dynamical Theory of Heat, Part VI. continued. A Mechanical 

 Theory of Thermo-electric Currents in Crystalline Solids. 

 By Professor W. Thomson, ..... 255 



On the Structure of Diatomacea. By E. W. Dallas, Esq. . 256 



Donations to the Library, .*.... 259 



