XX REPORT— 1839. 



Association at Bristol in 1836, and consisting of Sir John Robi- 

 son, K.H., Secretary of the Royal Society of Edinburgh, and 

 John Scott Russell, Esq., M.A., F.R.S. Edin. (Reporter). 



On the relative Strength and other mechanical Properties of 

 Cast Iron obtained by Hot and Cold Blast, by Eaton Hodgkinson. 



On the Strength and other Properties of Iron obtained from 

 the Hot and Cold Blast, by W. Fairbairn. 



1838. 



Account of a Level Line, measured from the Bristol Channel 

 to the English Channel, during the Year 1837-8, by Mr. 

 Bunt, under the Direction of a Committee of the British As- 

 sociation. Drawn up by the Rev. W. Whewell, F.R.S. , one 

 of the Committee. 



A Memoir on the Magnetic Isoclinal and Isodynamic Lines 

 in the British Islands, from Observations by Professors Hum- 

 phrey Lloyd and John Philhps, Robert Were Fox, Esq., Cap- 

 tain James Clark Ross, R.N., and Major Edward Sabine, 

 R.A., by Major Edward Sabine, R.A., F.R.S. 



First Report on the Determination of the Mean Numerical 

 Values of Railway Constants, by Dionysius Lardner, LL.D., 

 F.R.S., &c. 



First Report upon Experiments, instituted at the request of 

 the British Association, upon the Action of Sea and River 

 Water, whether clear or foul, and at various temperatures, 

 upon Cast and Wrought Iron, by Robert Mallet, M.R.I. A., 

 Ass. Ins. C.E. 



Notice of Experiments in progress, at the desire of the 

 British Association, on the Action of a Heat of 212° Fahr., 

 when long continued, on Inorganic and Organic Substances, 

 by Robert Mallet, M.R.I.A. 



Experiments on the ultimate Transverse Strength of Cast 

 Iron made at Arigna Works, Co. Leitrim, Ireland, at Messrs. 

 Bramah and Robinson's, 29th May, 1837. 



Provisional Reports and Notices of Progress in Special Re- 

 searches entrusted to Committees and Individuals. 



1839. 



Report on the present state of our knowledge of Refractive 

 Indices for the Standard Rays of the Solar Spectrum in dif- 

 ferent media. By the Rev. Baden Powell, M.A.,fF.R.S., F.G.S., 

 F.R.Ast.S., Savilian Professor of Geometry, Oxford. 



Report on the application of the sum assigned for Tide Cal- 

 culations to Mr. Whewell, in a Letter from T. G. Bunt, Esq., 

 Bristol. 



