[ iv ] 
XL Note on an Extension of the Comparison of Magnetic Disturbances with Magnetic 
Effects inf erred from observed Terrestrial Galvanic Currents; and Discussion of 
the Magnetic Effects inf erred from Galvanic Currents on days of Tranquil Mag- 
netism. By George Biddell Airy, Astronomer Royal , F.R.S. . . page 215 
XII. On Fluoride of Silver. By George Gore, F.R.S. 227 
XIII. On a distinct form of Transient Hemiopsia. By Hubert Airy, M.A . , M.D. 
Communicated by the Astronomer Royal, F.R.S 247 
XIV. Contributions to Terrestrial Magnetism . — No. XII. The Magnetic Survey of the 
British Islands, reduced to the Epoch 1842 - 5. By General Sir Edward Sabine, 
K.C.B., President of the Royal Society 2G5 
XV. On the Thermodynamic Theory of Waves of Finite Longitudinal Disturbance. 
By W. J. Macquorn Rankine, C.E., LL.D., F.R.SS. Bond. & Edin., &c. . 277 
XVI. On the Contact of Conics with Surfaces. By William Spottiswoode, M.A. , 
F.R.S 289 
XVII. On the Relation between the Sun’s Altitude and Jhe Chemical Intensity of Total 
Daylight in a Cloudless Sky. By Henry E. Roscoe, F.R.S., Professor of Che- 
mistry in Owens College, Manchester, and T. E. Thorpe, Ph.D., Professor of 
Chemistry in Anderson s University, Glasgow 309 
XVIII. Researches on Vanadium . — Part III. By Henry E. Roscoe, B.A., Ph.D., 
F.R.S 317 
XIX. On the Action of Rays of high Refrangibility upon Gaseous Matter. By John 
Tyndall, LL.D., F.R.S. 333 
XX. Tables of the Numerical Values of the Sine-integral, Cosine-integral, and Expo- 
nential-integral. By J. W. L. Glaisher, Trinity College , Cambridge. Commu- 
nicated by Professor Cayley, F.R.S 367 
XXI. Researches on Solar Physics. — No. II. The Positions and Areas of the Spots 
observed at Kew during the years 1864, 1865, 1866, also the Spotted Area of 
the Sun's visible disk from the commencement of 1832 up to May 1868. By 
Warren He La Rue, Esq., D.C.L., V.P.R.S. , F.R.A.S., Balfour Stewart, Esq., 
LL.D., F.R.S., F.R.A.S. , Superintendent of the Kew Observatory, and Benjamin 
Loewy, Esq., F.R.A.S 389 
XXII. On the Mechanical Performance of Logical Inference. By W. Stanley Jevons, 
M.A. ( Lond .), Professor of Logic Ac. in Owens College, Manchester. Commu- 
nicated by Professor H. E. Roscoe, F.R.S 497 
XXIII. On the Fossil Mammals of Australia . — Part III. Diprotodon australis, Owen. 
By Professor Owen, F.R.S. Ac 519 
