1855] WRITINGS OF JOSEPH HENRY. 355 



are stretched longitudinally and transversely. I here ex- 

 hibit to the Association a piece of iron — originally from a 

 square bar four feet long, which has been so hammered as 

 to produce a perforation of the whole length entirely through 

 the axis. The bar can be seen through as if it were the 

 tube of a telescope. 



This fact appears to me to be of great importance in a 

 practical point of view, and may be connected with many 

 of the lamentable accidents which have occured in the break- 

 ing of the axles of locomotive engines. These, in all cases, 

 ought to be formed by rolling and not with the hammer. 



The whole subject of the molecular constitution of matter 

 offers a rich field for investigation, and isolated facts which 

 are familiar to almost every one, when attentively studied, 

 will yield results alike interesting to abstract science and 

 to practical art. 



ON THE EFFECT OF MINGLING RADIATING SUBSTANCES WITH 

 COMBUSTIBLE MATERIALS. 



(Proceedings American Association Adv. of Science, vol. ix, pp. 112-116.) 

 August 17, 1855. 



I beg leave to call the attention of the Association for a 

 few moments to a paper published by our distinguished 

 countryman. Count Rumford, in 1802, in the first volume of 

 the Journal of the Royal Institution of Great Britain, page 

 28, entitled "Observations relative to the Means of Increas- 

 ing the Quantities of Heat obtained in the Combustion of 

 Fuel." 



"It is a fact," says Count Rumford, "which has long been 

 known, that clay and several other incombustible substances, 

 when mixed with sea-coal in certain proportions, cause the 

 latter to give out more heat in its combustion than it can be 

 made to produce when it is burnt pure or unmixed." 



" It has been ascertained that when the sides and back of 

 an open chimney fire-place, in which coals are burnt, are 



