ON AMERICAN PERMANENT WAT. 595 



VI. and VII., as adopted and in nse on a number of American roads. These 

 will repi'esent pretty fairly the general practice throughout the country. 

 In comparing these it must be borne in mind that the service on some 

 lines is not so severe as on others ; also that the same railroad company 

 uses lighter sections on its branch lines than on its main stem, on account 

 of the difference in service. Sections that are quite suitable in one case 

 are not so in others. 



The numbers by which the several sections are designated are those 

 of the Cambria Iron Company. "Where the roads using any section are 

 noted, and the date is given, it simply means that this section was rolled 

 for that railroad at that date. It does not follow that the railroad in 

 question may not have changed its section at some other mill since then ; 

 but this is a matter that could not be ascertained, and its probability is 

 not very great. 



The" Grand Trunk Railway of Canada uses the Sandberg pattern of 

 T rail, weight 60 pounds per yard. 



The Chicago and North-Western Railway Company are using 30-feet 

 rails, the weight on main lines since 1882 being 65 pounds per yard, on 

 less important lines 60 pounds per yard, and some 56 and 50 pound rails 

 on branches. 



The material of which rails are formed requires great care in selection. 

 It mast be sufficiently strong to sustain as a girder, tough to avoid all 

 brittleness and danger of breaking under sudden shocks, and at the same 

 time compact in texture and having hardness in the top to resist wearing 

 action under service. With iron rails it is sought to arrange for these 

 qualities in the packing or building up of the masses of iron from which 

 the rails are rolled, taking advantage of the well-known principle that the 

 different parts of the mass keep their same relative positions in the section 

 of the bar when rolled out as in the original pile. Harder material is put 

 in the top of the pile, and softer in the bottom. Steel rails, however, are 

 rolled from solid ingots, and as a consequence they are of a homogeneous 

 texture throughout. They do not split like iron rails, which sometimes 

 shows the result of imperfect welding between the separate pieces of which 

 the original pile from which the rail was rolled was formed. 



Rails are rolled to a certain maximum length, 30 feet being the usual 

 standard on American roads ; but there is always a certain proportion of 

 shorter rails allowed, which however must conform to regular specified 

 lengths, these being generally arranged to conform to the standard 

 spacings of the cross- ties. 



The following specification of the Pennsylvania Railroad Company 

 for steel rails, adopted January 27, 1879, may be regarded as a standard 

 for first-class manufacture : — 



' As it is the desire of the Pennsylvania Railroad Company to have on 

 the roads under their control none but first-class tracks in every respect, 

 and as the rails laid down on these tracks form an important part in the 

 achievement of this result, the Pennsylvania Railroad Company have 

 found it necessary to make certain demands in regard to the manufacture 

 of their steel rails, with which the different rolling mills and rail inspectors 

 will be required to comply : — 



' 1. The steel used for rails shall be in accordance with the 

 " pneumatic " or " the open hearth " process, and contain not less than 

 thirty nor more than fifty one-hundredths of one per cent, of carbon. 



'2. The result of tbe carbon test of each charge, of which the 



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