Laurance, L. Simple Calculations for Students of Visual Optics. De my 8vo. Pp. 72. N.D. Hatton Press. 4s. 6d.

-General and Practical Optics. 3rd edn. Demy 8vo. Pp. 370. 1920. Hatton Press. 21s.

-Visual Optics and Sight Testing. 2nd edn. Demy 8vo. Pp. 432. 1920. Hatton Press. 21s.

Orford, H. Modern Optical Instruments. Cr. 8vo. Pp. 100. 1919. Pitman. 48.

Rohr, M. Von. (edited by). Geometrical Investigation of the Formation of Images in Optical Instruments: embodying the results of scientific researches conducted in German Optical Workshops (Forming Vol. I. of "The Theory of Optical Instruments.") Translated by R. Kanthack. 8vo. Pp. 636. 1920. H.M.S.O. 45s.

Steinheil, A., and Voit, E. Applied
Optics: The Computation of Optical
Systems. Translated from the
German by J. W. French. 2 Vols.
Fcap. 4to. Vol. 1. Pp. 161.
1918. Vol. 2. Pp. 207.
Blackie. 158. vol.
per

1919.

Whittaker, E. T. The Theory of Optical Instruments. 2nd edn. Demy Svo. Pp. 80. 1915. Cambridge University Press. 3s. 6d.

Wright, L. Optical Projection. A Treatise on the use of the Lantern in Exhibition and Scientific Demontration. 5th edn. Revised by R. S. Wright. 2 parts. Part 1. The Projection of Lantern Slides. Cr. 8vo. Pp. 95. 1920. Longmans. 48. 6d.

g. Colour: Spectra.

Abney, Sir W. de W. Researches in Colour Vision and the Trichromatic Theory. 8vo. Pp. 432. 1913. Longmans. 25s.

Liveing, G. D., and Dewar, Sir J. Collected Papers on Spectroscopy. Roy. 8vo. Pp. 582. 1915. Cambridge University Press. 30s.

Lockyer, Sir J. N. Studies in Spectrum Analysis. 6th edn. Cr. 8vo. Pp. 270. 1904. Kegan Paul. Ss. 6d.

Lovibond, J. W. Light and Colour Theories, and their Relation to Light and Colour Standardization. 8vo. Pp.90. 1915. Spon. 7s. 6d.

-An Introduction to the Study of Colour Phenomena, explaining a New Theory of Colour based entirely on experimental facts, with applications to scientific and industrial investigations. 8vo. Pp. 48, 10 Plates. 1905. Spon. 7s. 6d. Lyman, T. The Spectroscopy of the Extreme Ultra-Violet. 8vo. Pp. 142. 1914. Longmans. 6s. 6d. Mees, C. E.K. An Atlas of Absorp

tion Spectra. Cr. 8vo. Pp. 85. 1909. Longmans. 6s. 6d.

Parsons, J. H. An Introduction to the Study of Colour Vision. Roy. 8vo. Pp. 316. 1915. Cambridge University Press. 12s. 6d.

Rood, O. N. Colour: a Text-Book of Modern Chromatics, with Applications to Art and Industry. 5th edn. Cr. 8vo. Pp. 338. 1910. Kegan Paul. 7s. 6d.

Roscoe, Sir H. E., and Schuster, Sir A. Spectrum Analysis. 4th edn. 8vo. Pp. 468. 1885. Macmillan. 258.

Silberstein, L. Report on the Quantum Theory of Spectra. Demy 8vo. Pp. 46. 1920. Adam Hilger.

58.

Watts, W. M. An Introduction to the Study of Spectrum Analysis. Svo. Pp. 336. 1904. Longmans. 12s.

Zeeman, P. Researches in MagnetoOptics. 8vo. Pp. 236. 1913. Macmillan. 7s. 6d.

h. Sound.

Barton, E. H. A Text Book on Sound. 2nd edn. Ex. Cr. 8vo. Pp. 704. 1919. Macmillan. 12s. 6d.

Richardson, O. W. The Electron Theory of Matter. 2nd edn. Demy 8vo. Pp. 631. 1916. Cambridge University Press. 21s.

Thomson, Sir J.J. The Corpuscular Theory of Matter. 2nd imp. Demy 8vo. Pp. 178. 1907. Constable. 7s. 6d.

-Electricity and Matter. Cr. 8vo. Pp. 170. 1912. Constable. 9s.

iii. RELATIVITY.

Carr, H. W. The General Principle of Relativity in its Philosophical and Historial Aspect. Cr. 8vo. Pp. 175. 1920. Macmillan. 7s. 6d. Conway, A. W. Relativity. Demy 8vo. Pp. 43. 1913. Bell. 2s. Cunningham, E. Relativity, the Electron Theory and Gravitation. 2nd edition. Demy 8vo. Pp. 154. 1921. Longmans. 10s. 6d. --The Principle of Relativity. Demy 8vo. Pp. 235. 1914. Cambridge University Press. 12s. Eddington, A. S. Space, Time, and Gravitation. An Outline of the General Relativity Theory. 2nd imp. Demy 8vo. Pp. 226. (1923) 19.1. Cambridge University Press.

158.

-Report on the Relativity Theory of Gravitation. 2nd edn. Demy 8vo. 1920. Paper covers, 68. Cloth, 8s. Physical Society of London (Fleetway Press).

Einstein, A. Relativity: The Special

and the General Theory. A Popular
Exposition. Translated by R. W.
Lawson. Cr. 8vo. Pp. 151. 1920.
Methuen. 58.

Freundlich, E. The Foundations of
Einstein's Theory of Gravitation.
Authorised English Translation by
H. L. Brose. Preface by A.
Einstein. Introduction by H. H.
Turner. Pp. 77. 1920. Cam-
bridge University Press. 58.

Robb, A. A. A Theory of Time and Space. Roy. 8vo. Pp. 380. 1914. Cambridge University Press. 158.

-The Absolute Relations of Time and Space. Demy 8vo. Pp. 90. 1921. Cambridge University Press.

58.

Schlick, M. Space and Time in Contemporary Physics. An Introduction to the Theory of Relativity and Gravitation. Rendered into English by H. L. Brose. 8vo. Pp. 99. 1920. Oxford: Clarendon Press. 6s. 6d.

Silberstein, L. The Theory of

Relativity. 8vo. Pp. 304. 1914. Macmillan. 12s. 6d.

Slosson, E. E. Easy Lessons in

Einstein. A Discussion of the more intelligible features of the Theory of Relativity. Cr. 8vo. Pp. 136. 1920. Routledge. 5s.

iv. CURRENT IN GASES. Thomson, Sir J. J. Conduction of Electricity through Gases. Pp. 686. 2nd edn. Demy 8vo. (at present reprinting). Cambridge University Press. 168.

Townsend, J. S. Electricity in Gases. 8vo. Pp. 512. 1914. Oxford: Clarendon Press. 16s.

-The Theory of Ionization of Gases by Collision. Cr. 8vo. Pp. 100. 1910. Constable. 4s. 6d.

Wilson, H. A. The Electrical Property of Flames and of Incandescent Solids. Cr. 8vo. Pp. 120. 1912. University of London Press.

Kaye, G. W. C. X-Rays: An Introduction to the Study of Röntgen Rays. 3rd edn. 8vo. Pp. 308. 1918. Longmans. 9s. 6d. Knox, A. V. General Practice and X-Rays. A Handbook for the General Practitioner and Student, with Chapters on the Production of X-Rays and Instrumentation by R. Knox. Cr. 8vo. Pp. 228. 1921. Black. 15s.

Knox, R. Radiography and RadioTherapeutics. 3rd edn. Super Roy. 8vo. 1919. Vol. I. Radiography. Pp. 384. 35s. Vol. II. Radio-Therapeutics. Pp. 222.18s.

Black.

Makower, W. The Radio-active Substances: their Properties and Behaviour. Cr. 8vo. Pp. 313. 1908. Kegan Paul. 7s. 6d.

-and Practical Geiger, H. Measurements in Radioactivity. Cr. 8vo. Pp. 161. 1912. Longmans. 68. 6d.

Morton, E. R. Text-Book of Radiology (X-Rays). 2nd edn. Demy 8vo. Pp. 280. 1918. Kimpton. 10s. 6d.

Mowat, H. X-Rays. How to Produce and Interpret Them. Demy 8vo. Pp. 216. 1915. Frowde and Hodder. 9s. 6d.

Pilon, H. The Coolidge Tube: its Scientific Applications, Medical and Industrial. Authorised Translation. 1920. Cr. Svo. Pp. 98. Baillière. 7s. 6d.

Raffety, C. W. An Introduction to the Science of Radio-Activity. Cr. 8vo. Pp. 220. 1909. Longmans. 68.

Rayleigh, Lord. The Becquerel Rays and the Properties of Radium. 2nd edn. Demy 8vo. Pp. 221. 1906. Arnold. 10s.

Richardson, O. W. The Emission of Electricity from Hot Bodies. New Edition in the press. Long

mans.

Rutherford, Sir E. Radio-active Substances and their Radiations. Demy 8vo. Pp. 699. 1913. Cambridge University Press. 17s. 6d.

Soddy, F. The Interpretation of Radium and the Structure of the Atom. 4th edn. Demy 8vo. Pp. 276. 1920. Murray. 15s.

-Radio Activity. Demy 8vo. Pp. 224. 1904. Benn Bros. 5s. Turner, D. Radium, its Physics and Therapeutics. 2nd edn. Cr. 8vo. Pp. 184. 1914. Baillière.

58.

Campbell, N. R. Modern Electrical Theory. 2nd edn. Demy 8vo. Pp. 412. 1913. Cambridge University Press. 168.

Cavendish, H. Electrical Researches: Written 1771-81. Edited by J. Clerk Maxwell. Demy 8vo. Pp. 479. 1879. Cambridge University Press. 18s.

Cumming, L. An Introduction to the Theory of Electricity. 4th edn. Cr. 8vo. Pp. 362. 1894. Macmillan. 8s. 6d.

Curry, C. E. Theory of Electricity

and Magnetism. Cr. 8vo. Pp. 458. 1897. Macmillan. 8s. 6d. Emtage, W. T. A. The Mathematical Theory of Electricity and Magnetism. 2nd edn. Cr. 8vo. Pp. 236. 1894. Oxford: Clarendon Press. 7s. 6d.

Ewing, Sir J. A. Magnetic Induction in Iron and Other Metals. 3rd edn. Demy 8vo. Pp. 411. 1900. Benn Bros. 12s. 6d. Finn, M. Experimental Electricity and Magnetism. Cr. 8vo. Pp. 436. 1915. Bell. 58.

Fitzgerald, G. F. The Scientific Writings of the late George Francis Fitzgerald. Collected and Edited with an Historical Introduction by Sir J. Larmor. 8vo. Pp. 640. 1902. Longmans. 15s. 6d. Fleming, J. A. Magnets and Electric Currents. 3rd edn. Cr. 8vo. Pp. 417. 1914. Spon. 6s.

Foster, G. C., and Porter, A. W. Elementary Treatise on Electricity and Magnetism. Founded on Joubert's Traité élémentaire d'Electricité." 3rd edn. 8vo. Pp. 653. 1913. Longmans. 128. Fournier d'Albe, E. E. The Electron Theory: a Popular Introduction to the New Theory of Electricity and Magnetism. 3rd edn. Cr. 8vo. Pp.346. 1918. Longmans. 7s. 6d. Glazebrook, Sir R. T. Electricity and Magnetism. An Elementary Text-book. Cr. 8vo. Pp. 448. 1904. Cambridge University Press.

108.

Gray, A. A Treatise on Magnetism and Electricity. 8vo. Pp. 498. 1898. Macmillan. 148.

Hadley, H. E. Magnetism and Electricity for Students. Gl. 8vo. Pp. 596. 1920. Macmillan. 7s.

-Magnetism aud Electricity for Beginners. New imp. Gl. 8vo. Pp. 376. 1920. Macmillan. 3s. 6d.

Hansel, C. W. Introductory Electricity and Magnetism. Cr. 8vo. Pp. 390. 1919. Heinemann. 4s. 6d. Heaviside, 0. Electromagnetic Theory. 3 Vols. Demy 8vo. 1893. Vol. 1. Pp. 488. 158. Vol. 2. Pp. 563. 15s. Vol. 3 Pp. 519. 268. Benn Bros.

Hedges, K. Modern Lightning Conductors. 2nd edn. Med. 8vo. Pp. 125. 1910. Crosby Lockwood.