MECHANICS AND USEFUL ARTS. 61 



thai this compression makes what would otlaerwise be a level 

 road oue continually uji-hill, there are persons who advocate a 

 yielding foundation, as there are those who insist on a springing 

 or yielding tire. The mere fact that our ordinary locomotive tires 

 must be occasionally re-turned is a suliicieut refutation of their 

 l^osition. 



A perfectly rigid bed or road-way, and as rigid wheels, is the 

 rule that is found by ex2)erience to be the best. Soon as a wheel 

 or tire gets " out of round," it becomes, in oi^eration, a hammer, 

 destroying the rail. Mr. ]3essemer, at a recent meeting of the 

 British Association at Nottingham, gave an exceedingly elaborate 

 and interesting account of his own system of manufacturing 

 steel, and showed the vast importance that branch of industry 

 had assumed since his patent had come into working operation. 

 By the old system, forty pounds of steel was the largest mass of 

 metal oj^erated upon ; but by his process as much as twenty -five 

 tons could be converted into steel in one heating. It had super- 

 seded iron wherever large castings were required, such as ord- 

 nance of large size, locomotive and marine engine-Teranks, I'ails, 

 etc. He mentioned, as showing the superior durability of steel 

 rails over those of iron, that at the station at Camden Town, at a 

 part of the line over which all the traffic passed, a steel rail was 

 placed on one side of the line, and an iron rail on the other, and 

 that seventeen faces of the iron were worn away, Avhile the first 

 face of the steel rail was still in working order. Steel rails put 

 down four years ago were still in working order. The first cost 

 of steel rails was, of course, much greater than that of iron, but 

 compensation was found for this in the greater durability. 



The superintendent of one of our most successful railroads in- 

 forms us that iron rails on that road average about seven or eight 

 years of life. Steel rails have been recently introduced, but the 

 test is not considered sufficient to afibrd proper data for an opin- 

 ion. Steel tires have been used on the I'oad several years, some 

 of them having already run 70,000 miles, and, while costing 

 double the j)rice of iron, their durability has proved that they are 

 superior to iron ones. No such performance, we are certain, can 

 be recorded for iron tires. The " best iron tires " — according to 

 Thomas Prosser, C. E., who has lately issued a pamphlet on'this 

 subject, which should be a satisfactory exhibit to our railroad men 

 — "average only 60,000 miles, during which time four of them 

 will grind up one ton of rails." 



It appears to be evident that our railroad companies will event- 

 ually save by replacing their iron rails, iron tires, iron Avheels, 

 and iron locomotive axles, with those of steel, the rails to be laid 

 on an unyielding and permanent foundation. Certainly, this sub- 

 ject of the comparative value of iron and steel for these pur- 

 poses is worthy more general attention than has been given it in 

 this country, especially in the construction and "plant" of new 

 lines of railways. 



The surprising results that have appeared where steel rails have 

 been laid alongside of iron rails, in places subject to very heavy 

 traffic, have already caused their adoption on nearly all lines for 

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