64 AXNUAL OP SCIENTIFIC DISCOVERT. 



ponce per pound, or rather less than £14 per ton ; and one favorite 

 pattern of two feet six inch wheel, weighing: nearly four hundred 

 weight, was sold, ready for boring, for £2 lOs. each. But so far 

 from their eheapness having ali»ne maintained them in use, they 

 Were long ago adoi)ted on the Grand Trunk Railway of Canada, 

 because they wore found, upon tlie whole, l)etter than Avrought 

 iron. We have l^efore us a letter, written, in 18r)9, by the late ^Ir. 

 A. M. Itoss, engineer to the Victoria Bridge, ]\Iontreal, upon this 

 subject, and which contains this statement, a statement wliieh we 

 know to have been conlirmcd by the subsequent experience of the 

 engineers of the Grand Trunk Railway. In the International 

 Exhil)ition of 18(52 were; a ])air of chilled wheels, two feet nine 

 inches in diameter, which liad run upward of ir)(),(H)0 mihis under 

 a heav}' post-oliiee van on the Ciran<l Trunk Railway, and, although 

 worn, they were still in good condition. We need not dwell upon 

 the severity of a Canadian winter, nor explain how for months 

 togother tiic road bed — and there is seldom much ballast — is 

 frozen as hard as rock. 



This, if anything, would be expected to try chilled wheels ; yet 

 they are regularly cmi)lovcd for tiie leading-wheels of i)ass(niger 

 engines; and breakages, altliougii not al)S()lutely unknown, are at 

 least as infrequent as those of the best makes of English railway 

 carriage-tires. 



It requires good iron for chilled wheels. That used in America 

 for this l)ranch of manufacture is mostly cold-blast charcoal iron; 

 and it has to be selected and mixed with care to oljtain the proper 

 qualities of sti'ongth and hardness of chill. The chill should be 

 from three-eighths to five-eighths of an inch deep, and should cover 

 tilt! wiiole tread and the wearing face of the flange. Chilled 

 wheels require especial provision for cooling after being cast, so 

 as to avoid internal strain from contraction. The wheels do not 

 all come out of exactly the same diameter ; but there is no diffi- 

 culty in mating them in ])airs of equal diameter, the greatest van- 

 ation in the iliameters of a thousand two-feet-nine-ineh wheels 

 hardly exceeding one-eighth of an inch. The machinery employed 

 for boring is such that the hole is necessarily in the centre, so that 

 no eccentricity is possible. The wheels wear evenly and very 

 slowly, until their diameter has been reduced by nearly half an 

 inch. American iron, of choice quality for chilled wheels, is now 

 being taken to St. Petersburg for casting there the wheels of all 

 the carriage and wagon stock of the St. Petersburo: and Moscoav 

 Railway. Heretofore the wheels for that line have been imported 

 largely from the States. Our own size of wheel has never been 

 adopted there ; and as the weight of disk-wheels increases in a 

 higher ratio than that of the increase of diameter simply, we pre- 

 sume that a three-feet-six-inch wheel, instead of weighing but 

 five hundred weight, as in English practice, would reach six hun- 

 dred weight. We learn that iron of the proper quality for chilled 

 wheels is likely to be introduced into this country, and that they 

 will ijrobably receive a fair trial. 



We believe that five American chilled railway wheels have 

 arrived in London, and. that they will be broken experimentally, 



