120 
INFLUENCE ON ROLLING STOCK, RAILS, AND ROAD-BED. 
The effect of the material of the tie on the rolling-stock is difficult 
to ascertain, and not much is known about the influence of metal ties. 
But it may be noted that on the German railways in 1883 the num- 
ber of tire breakages per 100 miles of line with wooden ties, metal 
cross-ties, and metal longitudinal ties, were respectively as 7.25 to 5.96 
to 2.74; showing the advantage of the long-tie system, by which the 
shock at rail-joints especially is diminished. 
The weight of the entire superstructure in itself aud the good tamp- 
ing of the ballast conduce to its quiet position, and serve to lessen 
the loss in rolling-stock and the cost of maintenance. 
0. P. Sandberg, the well-known expert on rails, says : 
" It is a great mistake to diminish the rail section in consequence of the adoption of 
metal ties, as has heen done on some railroads, for the metal in the tie can in no 
sense make up for the metal in the rail. The strong rail has the power of spreading 
the effect of the concussions from the rolling stock over several neighboring sleep- 
ers, thus dividing the effect, while the light, weak rail will concentrate the blows 
on one or two ties. 
"The heavy flange rail also is a sine qua non for the success of a metallic permanent 
way; if by ' permanency ' be meant anything approaching thirty years or more." 
In the Revue Generale des Chemins de fer, April, 1886, p. 200, a com- 
parative table is given, showing the respective durability of rails on 
ordinary roads with wooden cro ss-ties, and roads on metal ties with 
the Vautherin and the Hoheneg ger system (longitudinal ties 32 feet 
long with one cross-tie to each length), and the Hilf system (longi- 
tudinal tie of 24£ and 29^ feet length with one cross-tie to each length). 
The comparative results show : (1) That with the Vautherin system 
the wear is three times as much as with good wooden ties; (2) with the 
Hohenegger system the wear is four times as rapid; and (3) with the 
Hilf system it is four to five times as rapid as with wooden ties. 
Metal ties do not bend visibly like those of wood, but descend evenly, 
and the leverage of the momentum of deflection at the intersection of 
the rails and ties is greater than in the case of wooden ties; but if the 
strain be limited to, say, 4 tons per square inch tor iron, and about half 
as much again for steel, there is no fear for the resistance of metal 
sleepers. 
If the ballast inside the rails has not been properly packed, so that 
only the portions outside the rails sustain the whole load, the momen- 
tum of deflection will double, but even then there will be nothing to 
fear; but if, on the contrary, only the central portion of the tie be- 
tween the rails bear upon the ballast, the maximum momentum of 
deflection, which may thus be increased to five times its ordinary 
amount, will be transferred to the center of the tie. 
Experience has shown, however, that this will not occur if care be 
taken not to pack the central portion of the tie. 
Filling hollow sleepers with ballast having a certain amount of cohe- 
