ADDRESS. 2 



r 



combustion into the atmosphere. Therefore, when you have adopted 

 mechanical traction for your vehicles in towns you may largely reduce 

 one cause of fog. And if you diminish your black smoke, you will 

 diminish black fogs. 



In manufactories you may prevent smoke either by care in firing, 

 by using smokeless coal, or by washing the soot out of the products of 

 consumption in its passage along the flue leading to the main chimney- 

 shaft. 



The black smoke from your kitchen may be avoided by the use of coke 

 or of gas. But so long as we retain the hygienic arrangement of the 

 open fire in our living-rooms I despair of finding a fireplace, however well 

 constructed, which will not be used in such a manner as to cause smoke, 

 unless, indeed, the chimneys were reversed and the fumes drawn into 

 some central shaft, where they might be washed before being passed into 

 the atmosphei'e. 



Electricity as a warming and cooking agent would be convenient, 

 cleanly, and economical when generated by water power, or possibly wind 

 power, but it is at present too dear when it has to be generated by means 

 of coal. I can conceive, however, that our descendants may learn so to 

 utilise electricity that they in some future century may be enabled by its 

 means to avoid the smoke in their towns. 



Ileclianical Engineering. 



In other branches of civil and mechanical engineering, the reports in 

 1831 and 1832 on the state of this science show that the theoretical and 

 practical knowledge of the strength of timber had obtained considerable 

 development. But in 1830, before the introduction of railways, cast iron 

 had been sparingly used in arched bridges for spans of from 160 to 200 

 feet, and wrought iron had only been applied to large-span iron bridges on 

 the suspension principle, the most notable instance of which was the Menai 

 Suspension Bridge, by Telford. Indeed, whilst the strength of timber had 

 been patiently investigated by engineers, the best form for the use of iron 

 girders and struts was only beginning to attract attention, and the earlier 

 volumes of our Proceedings contained numerous records of the researches 

 of Eaton Hodgkinson, Barlow, Rennie, and others. It was not until 

 twenty years later that Robert Stephenson and William Fairbairn erected 

 the tubular bridge at Menai, followed by the more scientific bridge erected 

 by Brunei at Saltash. These have now been entirely eclipsed by the skill 

 with which the estuary of the Forth has been bridged with a span of 

 1,700 feet by Sir John Fowler and Sir Benjamin Baker. 



The development of the iron industry is due to the association of the 

 chemist with the engineer. The introduction of the hot blast by Neilson, 

 in 1829, in the manufacture of cast iron had effected a large saving of fuel. 

 But the chemical conditions which afiect the strength and other qualities 

 of iron, and its combinations with carbon, silicon, phosphorus, and other 

 substance?, had at that time scarcely been investigated. 



