IV • CONTENTS. 



PAGE 



XV. Contributions from the Physical Laboratory of Harvard 

 • College : — 



8. On the Induction Spark produced in Breaking a 



Galvanic Circuit betioeen the Poles of a Magnet. 



By B. O. Peirce, Jr 218 



XVI. Contributions from the Physical Laboratory of Harvard 



College : — 



9. Condensers and Geissler''s Tubes. By William P, 



Wilson 228 



XVII. On Viviparous Echini from the Kerguelen Islands. By 



Alexander Agassiz 231 



XVIII. On a Possible Explanation of the Method employed by 

 Nobert in Ruling his Test Plates. By William A. 



Rogers 237 



XIX. Mountain Surveying. By Prof. E. C. Pickering. . . 256 



XX. Height and Velocity of Clouds. By Prof. E. C. Pick- 

 ering 263 



XXI. Contributions from the Physical Laboratory of the Massa- 

 chusetts Institute of Technology : — 



8. An ExperimeJital Proof of the Law of Inverse 



Squares for Sound. By William W. Jacques 265 



9. Diffraction of Sound. By William W. Jacques 269 

 10. ComparUton of Prismatic and Diffraction Spectra. 



By Prof. E. C. Pickering 273 



XXII. On Photographs of the Solar Spectrum. By Robert 



Amory, M.D 279 



XXIII. A New Form of Induction Apparatus. ■ By Henry P. 



BOWDITCH 281 



XXIV. Hydrographic Sketch of Lake Tilicaca. By Alexander 



Agassiz 283 



XXV. Contributions from the Physical Laboratory of Harvard 

 College : — 



10. Distribution of Magnetism on Armatures. By Har- 



old AViiiTiNG 293 



XXVI. Contributions from the Physical Laboratory of Harvard 

 College : — 

 11. Change of Electrical Resistance in Wires by 



Stretching. By George S. Pine 303 



Proceedings 313 



List of the Fellows and Foreign Honorary Members 375 



Statutes and Standing Votes . . . . 383 



Index 395 



