iv CONTENTS. 



PACK 



XV. Contributions from the Physical Laboratory of Harvard 



College : — 



8. On the Induction Spark produced in Breaking a 



Galvanic Circuit between the Poles of a Magnet. 



By B. O. Teirce, 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 Experimental Proof of the Law of Inverse 



Squares for Sound. By William W. Jacques 265 



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

 10. Comparison of Pristnalic 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 Eorm of Induction Apparatus. By Henry P. 



BOWDITCH 281 



XXIV. Ilydrographic Sketch of Lake Titicaca. By Alexander 



Agassiz 283 



XXV. Contributions from the Physical Laboratory of Harvard 

 College : — 



10. Distribution of Magnetism on Armatures. By Har- 



(H.D Whiting 293 



XXVI. Contrilnitions from tlie Physical Laboratory of Harvard 

 College : — 

 11. Change of Electrical Resistance in Wires by 



Stretching. By George S. Pine 303 



Proceedings 313 



List op the Fellows and Foreign Honorary Members 375 



Statutes and Standing Votes 383 



I'^DEx 395 



