Vil CONTENTS OF VOL. XXI.—FOCRTH SERIES. 
Proceedings of the Geological Society :— 
Dr. Hector on the Geology of the Country between Lake 
Superior and the Pacific Ocean...............6.-.-- 987 
Dr. A. Gesner on Elevations and Depressions of the Earth 
in Worth Awmienca 2. {0 SFE ry. vs Oo. 5 SC 539 
On the Theory of Cylindrical Condensers, by M. J. M. Gaugain 539 
On the Production of Graphite by the Decomposition of Cy- 
anogen Compounds, by Dr. P. Pauli........ Ss Re > oh ee 
On Electrical Partial Discharges, by P. Riess.............- 542 
On the Freezing of Water and the Formation of Hail, by M. L. 
RN. SS Bas at oie 5, SS ORE, ee 543 
On an Apparatus for Experiments on Respiration and Perspira- 
tion) by Professor-Pettenkofer 2. 2... 25% «Sue ity RR oie ee 
DGC re pia o'er wiettin swiavs Gann ahpyniht tate ree ain ah & ptainiete Ree 547 
ERRATA. 
Page 322, line 20, for coordinates 2, y, z read the coordmates y, 2. 
— 323, lne 9, for > (wu, t, y, z) read (wt, y, Zz). 
— 324, line 2 from bottom, for behind, the opening in the screen must 
read behind the opening in the screen, 7 must. 
At page 373 the parentheses in lines 12, 13 left vacant should be filled 
in with the number 32. And at page 375 the following words 
explanatory of the Table at foot (which were accidentally omitted) 
should be supplied :— 
By means of the substitutions 
the preceding eight aggregates become developed into thirty-two, 
which together constitute the exhaustive Table in question. 
Page 376, line 2, for eight read thirty-two. 
PLATES, 
J. Illustrative of Mr. T. A. Hirst’s Paper on Ripples, and their relation 
to the Velocities of Currents. 
II. Illustrative of M. W. Siemens’s Paper ona Standard Measure of Re- 
sistance to Galvanic Currents, and Dr. Forbes‘s Paper on the Re- 
pulsion of a Rectilinear Electrical Current on itself. 
III. Illustrative of Mr. W. Dittmar’s Paper on a new Method of arranging 
Numerical Tables. 
IV. Illustrative of Mr. T. A. Hirst’s Paper on Ripples, and their rela- 
tion to the Velocities of Currents. 
V. Illustrative of Prof. Maxwell’s Paper on Physical Lines of Force. 
VI. Illustrative of Mr. J. J. Waterston’s Paper on a Law of Liquid Ex- 
pansion that connects the Volume of a Liquid with its Tempera- 
ture and with the Density of its saturated Vapour. 
