Ill 
Monday, 17 th 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, ls£ 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 Cubic 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 
