Effects of Temperature. 1 3 1 



to offer you some experiments illustrative of some of these 

 effects. 



A modern glass-house is generally a cone built of brick, 

 having its interior diameter at the base, varying from 58 to 

 60 feet, and its perpendicular height varying from 90 to 100 

 feet. The upper aperture through which the smoke ascends, 

 varies from 9 feet 6 inches to 10 feet in diameter. This cone 

 terminates at its base in substantial pillars of brick about 

 3 feet square, following the exterior inclination of the surface 

 of the cone, and united above by arches which spring from 

 pillar to pillar, and below by inverted arches beneath the 

 ground. 



Around the centre of the interior floor of this cone the 

 furnace is erected ; and around the exterior of the pillars 

 which support the main body of the cone, the glass-house is 

 extended by shed roofs, whose rafters bear against the exterior 

 of the brick cone, above the arches which connect the pillars. 

 This extension constitutes the manufacturing workshop, or 

 space occupied by the glass-making operatives. The in- 

 terior space around the furnace and within the pillars, is that 

 occupied by the founders, or the men whose duty it is to fill 

 the pots with raw materials for the production of glass, to 

 urge the fire, to examine from time to time the state of fusion, 

 and in short, to make from sand, alkali and lime, by the aid 

 of intense heat, the material which the glass-making opera- 

 tives subsequently convert by manipulation into glass. 



For very many consecutive hours during the process of 

 founding the raw materials, a thermometer placed at the 

 greatest possible distance from the furnace, but within the 

 area occupied by the founders, and freely suspended from a 

 rod projecting from the interior surface of one of the brick 

 pillars (a distance in the present instance = 20 feet 5 inches), 

 will indicate a temperature varying from 316 to 325 of 

 Fahrenheit. The founders have cool recesses, into which they 

 frequently retire during their work, but the average of tem- 

 perature here mentioned, viz. from 3 16 to 325, and frequently 

 very much beyond 325, they bear without experiencing any 

 inconvenience whatsoever. Strangers universally wonder at 

 the possibility of human beings existing in a situation in which 

 their clothes are continually scorched, while their naked skin 

 exhibits no marks of the effects of fire. I had myself often 

 wondered at the circumstance, until I made some experiments 

 to endeavour to ascertain the cause of such an anomaly. The 

 results of some of these experiments are curious from the ex- 

 tent of the ranges of the temperatures, and I have much plea- 



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