112 Account of the Roof of the Kdsipur foundery . [Feb. 



to attempt its description ; those who are fond of mechanical inventions, 

 will be amply gratified by an inspection of the whole, especially by the 

 ingenious contrivance for adjusting the angle of the slide rests and 

 cutters, for the exterior bevil of the gun : — the circular revolving tools 

 for turning the trunnions : — the crane carriage for the guns, &c. 



The self-acting principle by which the exterior of the gun is turned, 

 while the interior is bored, so as to save one half of the time, while it 

 ensures perfect concentricity of the outer and inner circles, is, we be- . 

 lieve, an invention of Major Hutchinson's, who took the opportunity 

 when on furlough, of visiting some of the principal founderies in 

 Europe, and studied to adopt every improvement suggested by their 

 inspection. 



The whole apparatus is driven by a small engine of 10 horse power, 

 which also works a circular, and a reciprocating, saw, and a loam -mill 

 for the casting moulds of the foundery. 



The superficial area of the hall is 8462 square feet ; to form an idea 

 of this magnitude, it may be mentioned that the noble edifice of the 

 new Town Hall in Birmingham, is gaid to contain a larger space than 

 any room in Europe, and' will accommodate between three and four 

 thousand persons sitting, or ten thousand standing ; that room is 140 

 feet long, by 65 feet broad, making a superficial area of 9100 feet, 

 which is only 638 feet more than the Kasipur apartment. 



The roof consists of 10 trusses, Plate VI. Fig. 1, each composed of. 

 a pair of cast-iron beams pitched at an elevation of }J&£ feet in the o 

 vertex, and tied together at foot by a horizontal chain supported in the 

 centre by a vertical rod suspended from the angle. The truss-frames 

 are 15 feet 4.6 inches apart : they support light cross-beams and rafters 

 of wood, upon which the planking of the roof is nailed. The weight 

 of one truss with its entire load and chain, is equal to about five and 

 half tons, diffused over the two iron beams. 



The chain is three inches deep by one inch thick, = 3 inches in 

 section, consequently the applicable force of tension of the chain is 

 3X9 =§= 27 tons, and the ultimate strength of it 3 X 27 =81 tons. 

 The above weight of five and half tons' diffused over the two beams, 

 = 2f tons on each beam, gives according to the sine of the angle of 

 elevation, a tension on the chains of about five and half tons, or only 

 one-fifth the stretching weight, or one -fifteenth of the ultimate strength 

 of the chains. 



The iron beams and chains were all proved before they were put 

 up, by suspending for several days without effecting the slightest ap- 

 parent alteration, a weight of six tons from the vertex, producing a 

 trial tension of about 12 tons, which is more than twice the actual 

 tension. 



