Shrinkage and Expansion of Cast Iron, &c. 1 1 



pairs of moulds, of all sizes, three times each day. These 

 occupied the floor of brick in different ranges, and pre- 

 sented a very large aggregate of heated surface when poured. 

 The quantity of metal thus formed into shot at each cast 

 was nearly a ton. In May 1796 the average temperature 

 of this workshop for several days during casting was 113* 

 Fahr. One day a spirit-of-wine thermometer burst in my 

 hand with a report like a pistol. Its greatest range of scale 

 was 1 20° : the passages betwixt the moulds, for the move- 

 ments of the pourers, were 1 30°. In all these extra tempe- 

 ratures I uuitbrmly observed that a considerable portion of 

 the shot, particularly in the third cast, passed the gauge with 

 difficulty, and many of these found unserviceable for car- 

 ronades, where the windage allowed upon the calibre of the 

 piece is less. In the middle of August in the same year, 

 during a period of very hot close weather, I made repeated 

 trials, and found the effects always proportioned to the 

 temperature of the workshop. I shall finish this paper with 

 the particulars of one day's observations. 



Temp, of Room. 

 1st Cast, 9 in the morning - - 65" 



in 3 minutes of casting rose to 80 

 in 10 to 112 



in 13 to 128 



in 20 to 140 



Greatest heat in 33 minutes, being three 

 minutes after the pouring had ceased, 156 

 From 128 to 136° I felt a sensation of cold similar to that 

 when approaching a fire in winter, accompanied by a con- 

 siderable degree of shivering. About 150° this sensation 

 wore oiF, and I felt comparatively comfortable. Perspira- 

 tion had now become so violent as to ooze through all parts 

 of my waistcoat, breeches, and stockings. The workmen 

 who carried the metal perspired in such a manner as to wet 

 their large sacking trowsers as if they had been soaked in 

 water. The moisture ran in such torrents from their faces 

 and arms, as to be distinctly heard hissing upon the heated 

 moulds. Their step and arms were more agitated than I had 

 ever before observed, and the sinews all over their bodies 

 were uncommonly large, and felt inflated to a great degree. 

 Two men performed the whole labour of pourmg ; so that 

 each of them in 32 minutes carried half a ton of metal in 

 quantities, in hand-ladles, from forty to fifty pounds each 

 tnne. The space gone through each time, the return with 

 the empty ladle iiacludcd, was nearly 120 feet, or fullv 



equal. 



