CONTENTS OP N^ 161.— Fourth Series. I. On Chinese ABtronomical Epochs. By Archdeacon J. H. Pratt, M.A page II. Experiments on the Compaiative Effects of Noctomal Radiation from the Surface of the Ground and over a large Sheet of Water. Bj Professor Mabcxt of the Academy of Gkneva III. On Physical Lines of Force. By J. C. Maxwkll, F.R.S., Phi- fessor of Natural Philosophy in King's College, London ll IV. On the Direction of the Joints in the Faces of Obliqne Arches. By G. B. AiBT, Esq., Astronomer Royal S V. On the Relation of the Lateral Contraction to the Longitodioal Expansion in Rods of Spring Steel. By G. Kirchhoff. (With a Plate.) S VI. Notes on Mineralogy. By the Rev. Samusl Haughton, M.A.) F.R.S., Fellow of Trinity College, and Professor of Geology in the University of Dublin 4 VII. On the Fourth Law of the Relations of the Elastic Force, Deo- sity, and Temperature in Gases. By Professor Pottkr, A.M 2 VIII. On the Solar Spectrum, and the Spectra of the Chemical Elements. By Professor H. E. Roscos ( IX. On the inapplicability of the new term " Dyas " to the " Per- mian " Group of Rocks, as proposed by Dr. Geinitz. By Sir Rodrrick Imprt MnacHisbir, F.R.S., D.C.L., LL.D. &c.. Director- General of the Geological Surrey of Britain C X. Notices respecting New Books : — Euclid's Elements of Geometry, designed for the use of the higher Forms in Public Schools and Stn- dents in the Universities. By Robrrt Potts, M.A., Trinity College, Cambridge ] XI. Proceedings of Learned Societies : — RoTAL Socirtt: — The Rev. H. Mosrlkt on the Motion of a .' Plate of Metal on an Inclined Plane, when dilated and contracted; and on the descent of Glaciers '. XII. Intelligence and Miscellaneous Articles : — On the Conductibility of Saline Solutions, by M. Marie-Davy . . '
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