CONTENTS. VU 



Page 



Dr. J. Janssen sur le Spectroscope de poche 10 



. sur le Spectre Atmospheriqiie Terrestre et celui de la vapeur 



d'eau 11 



Professor John H. Jellett on a Fluid possessing Opposite Rotatory Powers 



for Rays at Opposite ends of the Spectrum 12 



Mr. Cornelius Vabley on Comets, and especially on the Comet of 1811 . . 12 



Heat. 



Dr. J. P. Joxile's determination of the Mechanical Equivalent of the Thermal 

 Unit by Experiments on the Heat evolved by Electric Currents 12 



Electeicitx. 



Mr. W. Hooper on the Electrical and Mechanical Properties of Hooper's 

 India-rubber Insulated Wire 13 



Mr. E. Hopkins on the Depolarization of Iron Ships, to prevent the Deviation 

 of the Compass 13 



Extract of a Letter from Senhor Capello, of the Observatory Lisbon, on 

 Magnetic Disturbance, to Balfour Stewart, of the Kew Observatory. ... 13 



Mr. C. F. Varley on certain Phenomena which presented themselves in Con- 

 nexion with the Atlantic Cable 14 



on a New Method of Testing Electrical Resistance , 14 



Meteoeologt. 



Sergeant Arnold on the Climate of Aldershot Camp 15 



Dr. Buys-Ballot on the Method adopted at Utrecht in discussing Meteorologi- 

 cal Obsei-vations 16 



Mr. Francis' Galton on an Error in the usual method of obtaining Meteor- 

 ological Statistics 16 



on the Conversion of Wind-charts into Passage-charts 17 



Mr. J. Park Harrison on the Heat attained bv the Moon under Solar Radi- 

 ation : 20 



Professor Hennessy on the Diurnal Period of Temperature in relation to other 

 Physical and Meteorological Phenomena 21 



on Meteoric Showers considered -wdth reference to the 



Motion of the Solar System 21 



Dr. W. J. Macquohn Rankine on a Table of Pairs of Stars for approximately 

 finding the Meiidian 21 



Instruments. 



Mr. John Bro'wning on some Recent Improvements in Astronomical Tele- 

 scopes with Silvered Glass Specula 22 



Mr. L. Casella on a New Anemometer 23 



Mr. A. Claudet on a Variable Diaphragm for Telescopes and Photographic 



Lenses 23 



on a Magnifying Stereoscope with a Single Lens 23 



Mr. J. Glaisheb's experiments off Ventnor with Mr. Johnson's Deep-sea 

 Pressure-gauge 24 



