n CONTENTS. 



Page 

 XI. Observations on the spontaneous emissions of inflammable Gas, in 

 particular of Carburetted Hydrogen. By Robert Bald, Esq. 

 F. R. S. E. &c. &c Communicated by the Author, . 71 



XII. On a solid form of Cyanogen or its Elements, and a new compound 

 of Carbon and Azote. By James F. W. Johnston, M. A. Com- 

 municated by the Author, . . 75 



XIII. A Letter to the Right Hon. T. P. Courtenay, on the proportion- 

 ; ^ .'Bte number of Births of the two Sexes under different circumstances. 



By Charles Babbage, Esq. M . A. F. R. S. Lond. and Edin. Lu- 

 casian Professor of Mathematics in the University of Cambridge, &c. 

 Ac. Communicated by the Author, . . 85 



XIV. Notice respecting a Method of producing an intense heat from Gas for 

 various purposes in the arts. By David Brewster, LL. D., 



F. R. S. L. and E. . . . 104 



XV. Account of a New Monochromatic Lamp depending on the combus- 

 tion of compressed Gas. By David Brewster, LL. D. F. R. S. L. 

 and E. . . . . 108 



XVI. On the Law of the Colours seen by transmission through grooved 



Surfaces. By M. Babinet, . . 109 



XVII. Theory of the colours observed in the experiments of Fraunhofer. 



By Thomas Young, M. D. F. R. S. . . 112 



XVIII. Notice of a Remarkable Electrical Cloud. By the Reverend John 

 Macvicar, a. M. Lecturer on Natural Philosophy in the Univer- 

 sity of St Andrews. Communicated by the Author, . 117 

 XIX. On the atomic constitution of the Cyanide of Mercury. By J. F. W. 



Johnston, M. A. Communicated by the Author, . 119 



XX. Physical Notices of the Bay of Naples. No. I V. On the Solfatara 

 of Pozzuoli. By James D. Forbes, Esq. Communicated by the 

 Author, . . . . 124 



XXI. Researches on the Elasticity of regularly crystallized Bodies. By 



M. Felix Savart, . . . 141 



XXII. On the Art of forming Diamonds into Single Lenses for Microscopes. 

 By Andrew Pritchard. Communicated by C. R. Goring, 

 M.D. . . . . . 147 



XXIII* Remarks on the structure of the Gibbons, a subgenus of the Orangs 

 or Pitheci. By Dr Knox, F. R. S. E. Lecturer on Anatomy. Com- 

 municated by the Author, . . .155 



XXIV. ZOOLOGICAL COLLECTIONS, . . 157 



I. Notice regarding the Osteology and Dentition of the Dugong. By 



Dr Knox, . . . . ib. 



2. Baron Cuvier's great work on Fishes, . • .158 



XXV. HISTORY OF MECHANICAL INVENTIONS AND OF PRO- 

 CESSES AND MATERIALS USED IN THE FINE AND 

 USEFUL ARTS, . . 162 



1. Account of an improved Air Pump. By the Reverend John 

 Macvicar, A. M. Lecturer on Natural Philosophy in the Univer- 

 sity of St Andrews. Commi.micated by the Author, . ib. 



