1841.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



157 



This diSerence in tlie fusibility of the various states of iron affords 

 a clue to the mystery which seems to have puzzled Drs. Ure and 

 Karsten, who may perhaps have still to learn that charcoal never com- 

 bines with iron after it has become fluid, and that the union is always 

 effected by a process of cementation. 



Suppose then that an experimentalist were in the first instance to 

 fuse refined metal (which is the whitest of white iron), with a certain 

 portion of charcoal, and to obtain a soft gray granular metal, this re- 

 sult would be uniformly obtained so long as the same substances were 

 used, but were be to substitute for the refined metal, white cast 

 iron, (which, to an unpractised eye, is not easily distinguishable from 

 the other), and fuse it with the same, or with a greater quantity of 

 charcoal, the result would not in this case be gray, but white cast iron, 

 of the same appearance as when introduced into the crucible. 



But it by no means follows that white pig, or cast iron, cannot be 

 converted into gray iron in the crucible, for however great its fusibility, 

 yet if a portion of those earths whose affinities for carbon are deve- 

 loped at page 553 of my work, be introduced into the crucible and 

 fused along with white cast iron, and even a minimum doze of carbon, 

 the result will be gray iron of the best quality. In short the same iron 

 which when fused with half its weight of charcoal alone, comes out of 

 the cruc'ble white, will by the introduction of the earths be converted 

 into rich gray iron with an increase of weight, and this result will be 

 obtained with only 5*5 or ^ of its weight of charcoal. 



Your's, &c., 

 D. MUSUET. 



(To be continued.) 



THE LARGE WATER WHEEL AT COLEBROOK DALE. 



Sir- — Thinking a short description of a water-wheel of no ordinary 

 dimensions may be worth your notice, I send a slight sketch and a few 

 of the principal dimensions of one erected in Colebrook Dale, Shrop- 

 shire, it works an oil and colour mill, but as the speed and the supply 

 of water vary considerably, no correct estimate of the power can be 

 obtained, but it probably does not exceed 3 or 4 horses' power. The 

 speed is generally about one revolution in three minutes, or 1-39 feet 

 per second ; part of the water comes on to the wheel at the top and 

 part about "25 feet lower down. 



Fig. 1. 



The principal dimensions are as follows: — diameter out to out, SO 

 feet, 28 arms B, S inches by 3 inches ; side stays C, two to each arm, 

 4 inches by 3 inches ; the arms and stays are braced together by two 

 circles D D, 4 inches by 3 inches ; and by cross stretchers E, of the 



FiK. 4. 



Fig. 5. 



I'-ig. 6. 

 p-iSl 



-f 



Scale of enlarged parts figs. 3, 4. 3, 6— quarter inch equal to a foot. 



same dimensions. The buckets, of which there are 280, are 9 in. 

 wide at the top, 5 in. at the bottom, 15 in. in breadth, and 10^ in. 

 deep. The shaft A is of cast iron hollow, 14 ft. y in. long between 

 the bearings, 26 in. diameter, with mortice holes cast in to receive 

 the arms and side stays. The arms are of pitch pine, all the other 

 parts are oak. The spur wheel F is 15 feet diameter. The breadth 

 of the lines in the drawing are as near as may be the dimensions of the 

 different parts. 



Fig. 1 is an elevation of the wheel ; fig. 2 a section ; fig. 3 an en- 

 larged section of the shaft A taken longitudinally, showing the man- 

 ner in which the arms B B, and stays C, C, C, C, are fixed, and the 

 spur wheel E, E ; fig. 4 a transverse section of the shaft from a to b, 

 showing the arms ; fig. 5 is a section ; and fig. 6, front view of the 

 buckets. 



I remain, &c. 



H. C. 



Railway Works in France. — The Havre Journal, in noticing the arrivals of 

 wagons and workmen for the Paris and Rouen Railroad in that port, says 

 that the wagons have been hired from the London and Southampton Com- 

 pany at a much loHer price than they could possibly have been in France, 

 and that the Borknien Mho have been sent over, are all chosen from the most 

 sober and laborious of their class that could le found in England. This 

 journal takes the opportunity of pointing out the activity and energy shown 

 l)y the English engineers, and the Paris and Rouen Company, and holds up 

 their example to the notice of all engaged in France on similar works. 



