VIU CONTENTS. 



Page 



Mr. W. H. Russell on the Mechanical Tracing of Curves 15 



Professor Sylvester on Professor Christian Wiener's Stereoscopic Represen- 

 tation of the Cubic Eikosi-heptagram 15 



on the Successive Involutes to a Circle 15 



AsTEOiroMT. 



Mr. W. R. BiBT on Secular Variations of Lunar Tints and Spots and Shadows 



on Plato 15 



Mr. William Huggins on the Heat of the Stars 18 



The Rev. R. Main on the Lon^tude of the RadclifFe Observatory, Oxford, as 

 deduced fi'om Meridional Observations of the Moon, made at Greenwich 

 and Oxford, in the years 1864-68 18 



on the Discordance usually observed between the results of 



Direct and Reflexion Observations of North Polar Distance IS 



's Remarks on the British Association Catalogue of Stars . . 19 



Dr. A. Neumayee on the recent fall of an Aerolite at Ea-ahenburg in the Pa- 

 latinate 20 



The Rev. Dr. Robinson on the Appearance of the Nebula in Argo as seen in 



the Great Melbourne Telescope 20 



Professor P. G. Tait on Comets 21 



Optics. 



Mr. Chaeles Beooke on the Influence of Annealing on Crystalline Structure 21 



Dr. J. H. Gladstone on the Relation between the Specific Refi-active Energies 



and the Combining Proportions of Metals 22 



Dr. Janssen's Methode poiu' obtenir les Images Monochromatiques des Corps 



Lumineux 23 



The Rev. Professor Jellett on a Method by which the Formation of certain 



definite Chemical Compounds may be Optically established 23 



Professor Aug. Moeeen on the Chemical Action of Light discovered by Pro- 

 fessor Tyndall 24 



Mr. G. Johnstone Stoney on the Numerical Relations between the Wave- 



Lengths of the Hydrogen Rays 24 



Heat. 



Professor Gustav Magnus on the Absorption, Emission, and Reflection of 



Heat 25 



Meteoeologt. 



Mr. Rogers Field and G. J.Symons on the Determination of the Real Amount 



of Evaporation from the Surface of Water 25 



Mr. James Glaisher on the Changes of Temperature and Humidity of the 

 Air up to 1000 feet, from observations made in the Car of M. GiflPard's 

 Captive Balloon 27 



Dr. Henry Hudson on the Formation of Dew, and its Efiects 39 



Dr. Janssen's Faits divers de Physique Terrestre 41 



Dr. Mann on the Rainfall of Natal, South Africa 41 



Mr. Balfoue Stewaet's Remarks on Meteorological Reductions, with 



especial reference to the Element of Vapour 43 



