MECHANICS AXD USEFUL ARTS. 33 



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regenerative chamber, so that it also may be strongly heated. Thus 

 both the gaseous fuel and the air for burning it enter the furnace at a 

 high temperature. But, while this is going on, the products of com- 

 bustion must, on their -way to the stack, be compelled to traverse the 

 other two cold regenerative chambers, to the brickwork of which 

 they will in great measure deliver up their heat. When these shall 

 have become heated, the other two chambers will have become 

 cooled ; and then we will change the direction of the currents, 

 diverting the course of the gaseous fuel and the gas intended to 

 support combustion, and sending them through the last heated cham- 

 bers respectively. And thus the process may be continued, alternating 

 rix>rn time to time the direction of the currents. It is obvious that by 

 this means the waste heat is in a great measure caught by the brick- 

 work in the regenerative chambers, and subsequently restored to the 

 furnace. So much, indeed, is this the case, that when the interior of 

 the furnace is white-hot the temperature of the products of combus- 

 tion escaping from the chimney does not exceed three hundred 

 degrees Fahrenheit. The temperature which may be attained in the 

 furnace is enormous, and may be regulated to a nicety. Prof. Faraday, 

 in a recent lecture before the Royal Institution, London, described 

 in eloquent terms the impression produced on his mind when he saw 

 these furnaces in operation at a large glass manufactory in Birming- 

 ham. One furnace contained twelve pots, each of which held two 

 tons of glass ; and yet, on one occasion, so high was the temperature, 

 that the whole was actually melted down ! If we reflect, we shall 

 perceive that Siemens's principle is precisely that on which a hand- 

 kerchief is tied round the mouth, or a " respirator " applied to it on a 

 frosty day. The word " accumulative " would, probably, be more ex- 

 pressive than " regenerative." There is no regeneration, but simply 

 retention and accumulation. 



Of Patent Fuel there were numerous examples illustrative of va- 

 rious patent processes. In general the principle upon which these 

 preparations is based is the agglomeration of fine coal, which is 

 effected by the intermixture of pitchy matter. The compound is 

 fashioned in bricklike or cylindrical lumps of convenient size under 

 pressure, with or without the application of moderate heat, according 

 to circumstances. Elaborate machinery for preparing this fuel was 

 exhibited in the Belgian department. 



India-Rubber Substitute. In the section of India-rubber goods, an 

 exhibition was made of the so-called " campticon," or India-rubber 

 substitute. This new product is made from oxidized oil, so treated as 

 to remove all unctuous matter, and is formed into a semi-elastic resin, 

 which for many purposes, such as steam-packing, driving bands, and 

 hose, is said to answer equally as well as India-rubber, at a considera- 

 ble less cost. It can be supplied in cither dough or solution, and as a 

 hard compound vulcanizes as readily as India-rubber, without the use 

 of sulphur. 



Artesian Well-boring. --It was stated in connection with certain 

 improved machinery exhibited for boring Artesian wells, by Degousee, 

 of Paris, that to such perfection has earth-boring been now carried, 

 that solid cylinders of the rocks, perforated at extreme depths, may be 

 obtained in the position which they occupied, and the actual dip of 



