146 



cussion of the air has a tendency to facihtate tlie conversion 

 of rain-forming material into actual drops of rain, then we 

 may well suppose that the violent concussions produced by 

 lightning discharges, acting on such enormous and dense 

 masses of rain-forming material as are usually collected in 

 heavy thunder clouds, are amply sufficient to produce these 

 sudden and heavy showers of rain. 



I am aware that the eiFect of a discharge of ordnance is 

 usually supposed to be produced by an upward current of air 

 caused by the heat and the gases evolved during the com- 

 bustion of the gunpowder ; but as an hour's sunshine through 

 an opening in the clouds, especially when the sun is at a 

 considerable altitude, would produce a much greater effect in 

 heating and increasing the bulk of the air, this cannot be 

 received as the true explanation of the mode in which the 

 effect of a discharge of heavy artillery is produced. 



Mr. Fairbairn stated that he had been making experi- 

 ments on the process of cold rolling, as applied to iron. He 

 had tested specimens of cold rolled iron manufactured both 

 by Mr. Lauth and Earl Dudley. In the former case, a black 

 bar from the rolls broke with 26' 173 tons per square inch, a 

 a similar turned bar with 27" 11 9 tons, and a cold rolled bar 

 of the same iron sustained 39*o88 tons. The elongations, 

 which may be considered as the measure of ductility, were 

 •200 and '220 per unit of length in the case of the ordinary 

 iron, and "079 in the cold rolled iron. A plate of cold rolled 

 iron, from Earl Dudley, sustained no less than 51*3 tons 

 per square inch. Endeavours were being made to apply the 

 invention to railway bars. 



Mr. Brockbank described the Bessemer process of manu- 

 facturing iron and steel, and stated his belief that the 

 variously colored flames on the surface of newly run steel 

 would afford the means of detecting the presence of metals 

 and other bodies by the new method of spectrum analysis. 



