CONTENTS— {continued) : 



PAGE 



Y. Preliminary Report to Professor Wyville Thomson, F.E.S., Director of 

 the Civilian Scientific Staff, on Work (Chemical and Geological^ done on 

 board H.M.S. ' Challenger.' By J. Y. Buchanan, Chemist and Physicist 

 to the Expedition 388 



March 23, 1876. 



I. On the Force caused by the Communication of Heat between a Surface and 



a Gas, and on a New Photometer. By Prof. Osborne Reynolds . . . 388 



II. On the Nature of the Force producing the Motion of a Body exposed to 

 Rays of Heat and Light. By Arthur Schuster, Ph.D., Demonstrator 

 in the Physical Laboratory of Owens College 391 



II. On the Number of Figures in the Period of each Reciprocal of a Prime from 



53,000 to 60,000. By W. Shanks 392 



Y. On a new Refractometer for measuring the Mean Refractive Index of Plates 

 of Glass and Lenses by the employment of Newton's Rings. By G. W. 

 RoYSTpN^PmoTT, M.A., M.D. Cantab., F.R.S., F.R.A.S., F.GP.S. . . .393 



V. Description of a Mammalian Ovum in an early condition of Development. 

 By Edward Albert Schaeer, Assistant Professor of Physiology in Uni- 

 versity College, London 399 



yi. Preliminary Report to the Hydrographer of the Admiralty on some of the 

 Results of the Cruise of H.M.S. \ Challenger ' between Hawaii and Valparaiso. 

 By Prof. Wyville Thomson, F.R.S., Director of the Civilian Scientific 

 Staff on board 403 



March 30, 1876. 



I. An Experiment on Electro-Magnetic Rotation. By W. Spottiswoode, M.A., 



Treas. and y.P.R.S 403 



II. The Residual Charge of the Ley den Jar. By J. Hopxinson, M.A., D.Sc. . 407 

 III. On the Placentation of the Lemurs. By Wm. Turner, M.B. (Lond.), Pro- 

 fessor of Anatomy, University of Edinburgh 409 



iy. On the Movement of the Glass Case of a Radiometer. By William 



Crookes, F.R.S. &c 409 



List of Presents 410 



Preliminary Note on the Anatomy of the Umbilical Cord. By Lawson Tait, 

 F.R.C.S. &c 417 



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