MECHANICS AND USEFUL ARTS. 63 



found that at the expiration of three years and three months, the 

 surface was evenly worn to the extent of only a little more than a 

 quarter of an inch, and to all appearance they were capable of 

 enduring a great deal more work. These two i-ails had, during 

 the period of a little more than three years, been exjjosed to the 

 traffic of 9,550,000 engines, trucks, and carriages, and 95,577,240 

 tons. It is an amount of traffic equal to nearly ten times that 

 which destroyed the Great Northern rails above referred to in 

 three years. The result of this trial was to induce the London 

 and Northwestern to enter very extensively into the employment 

 of steel rails ; and we learn from Mr. Webb that in a short time 

 arrangements will be made at Crewe for the production of three 

 hundred and fifty tons of steel per week, of which three hundred ' 

 will be used for rails ; and that at the present time there are about 

 fifty miles of steel rails in use on the line, and three thousand tons 

 of steel-headed rails." 



An examination of the steel rails laid down two years and a half 

 since in the Woodhead Tunnel of the Manchester, Sheffield, and 

 Lincolnshire Railway, resulted in a striking illustration of the I'el- 

 ative endurance of steel and iron rails. This tunnel is about three 

 miles long, v/ith a station at each end, where trains generally stop, 

 and where the wear of the rails is extraordinary, from the starting 

 of heavy trains with the aid of sand on iron constantly wet with 

 drippings from the roof. The life of an iron rail at these stations 

 was but about five months on one head, and three or four months 

 . on the other, after turning. The new rails are seventy-five pounds 

 Bessemer steel, double-headed, two and a half inch face, five- 

 oighths inch stem, and five inches deep. Rails were taken out at 

 the places of greatest wear, at each end of the tunnel, and on 

 being carefully measured and compared with the original tem- 

 plates from which they were made, were found to have lost as 

 nearly as possible one-eighth of an inch in the thirty months' use, 

 under at least 8,000,000 tons of traffic, as computed from the books 

 of the station. The rails were in admirable condition, and good 

 for five times as much further wear, both heads together ; making, 

 in insurance phrase, an " expectation of life " equal to fifteen 

 3'cars, or twenty times as long as that of iron. — Svientijic Ameri- 

 can, 1866. 



CHILLED RAILWAY WHEELS. 



The practice with Major Palliser's shot against armor has shown 

 what are the qualities of chilled cast-iron ; the chill, in this case, 

 extending quite through the casting. It has been demonstrated 

 that it is equal in hardness to hardened steel, and that it requires 

 even greater force to break or deform it. It may be that the 

 startling results obtained at Shoeburyness will serve, in some 

 measure, to account for the universal use of chilled railway wheels 

 in America, and for the leading wheels of engines, and often for 

 the driving-wheels themselves as well. It has always been the 

 belief in this countr}^ that those wheels were used liecause they 

 were cheap, and because the Americans could aft'ord nothing bet- 

 ter. These wheels, before the war, cost about one and a half 



