XXVI 



On the Action of the Second Surfaces of transparent Plates upon 

 Light. By David Brewster, LL.D. F.R.S. L.&E page 395 



Observations made with the Invariable Pendulum (No. 4. Jones), at 

 the Royal Observatory, Cape of Good Hope, for the purpose of 

 determining the Compression of the Earth. By the Rev. Fearon 

 Fallows, F.R.S 396 



Statement of the principal Circumstances respecting the united Siam- 

 ese Twins now exhibiting in London. By George Buckley Bolton, 

 Esq 397 



On some Properties in Achromatic Object-glasses applicable to the 

 Improvement of the Microscope. By Joseph Jackson Lister, Esq. 399 



On the Pendulum. By J. W. Lubbock, Esq. F.R.S 401 



On the Theoretical Investigation of the Velocity of Sound, as cor- 

 rected from M. Dulong's recent Experiments, compared with the 

 Results of the Observations of Dr. Moll and Dr. Van Beek. By 

 Dr. Simons 401 



On the Elasticity of Threads of Glass, with some of the most useful 

 Applications of this property to Torsion Balances. By William 

 Ritchie, A.M. F.R.S 402 



Memoir on the occurrence of Iodine and Bromine in certain Mineral 

 Waters of South Britain. By Charles Daubeny, M.D. F.R.S 402 



Experiments to determine the Difference in the Number of Vibrations 

 made by an Invariable Pendulum in the Royal Observatories of 

 Greenwich and Altona. By Captain Edward Sabine, Sec. R.S. . 403 



Experiments to ascertain the Correction for Variations of Tempera- 

 ture, within the limits of the natural Temperature of the Climate 

 of the South of England, of the Invariable Pendulum recently em- 

 ployed by British Observers. By Captain Edward Sabine, Sec. R.S. 404 



On anew Register- Pyrometer, for measuring the Expansions of Solids, 

 and determining the higher Degrees of Temperature upon the com- 

 mon thermometric Scale. By J. Frederic Daniell, Esq. F.R.S. ... 404 



On the Phenomena and Laws of Elliptic Polarization, as exhibited in 

 the Action of Metals upon Light. By David Brewster, LL.D. F.R.S. 

 L. & E 406 



Researches in Physical Astronomy. By John William Lubbock, Esq. 

 F.R.S 408 



On the Error in Standards of Linear Measure, arising from the thick- 

 ness of the Bar on which they are traced. By Captain Henry Kater, 

 V.P. andTreas. R.S 408 



On the Illumination of Light-houses. By Lieutenant Thomas Drum- 

 mond 410 



On the Electro-magnetic Properties of metalliferous Veins in the Mines 

 of Cornwall. By Robert Were Fox 411 



Sequel to a Paper on the tendency to Calculous Diseases, and on the 

 Concretions to which such Diseases give rise. By John Yellolv, 

 M.D. F.R.S. &c. ,412 



