Page:Popular Science Monthly Volume 29.djvu/634

616 the ties were sound, and would not be called decayed. In the yellow pine the spikes check and separate the. annular rings, which permits the entrance and growth of the mycelium of its special fungus, and this weakens the fiber and loosens the spike. In white oak and chestnut the layers separate by breaking through the small tracheids surrounding the ducts (see Fig. 3, August number), those of the chestnut more rapidly. The fermentations are retarded in these woods by the tannin in the cells, but they take place eventually, softening and injuring the fibers around the spikes and under the rails.

In ties which are well treated, so as to preserve them, the fermentations are held in check, and the softening of the fibers is prevented, and their durability and consequent wearing capacity are increased. This is an advantage so important that its full benefits can not be appreciated until actual comparisons are made between treated and untreated ties under similar conditions of service. I have parts of treated ties of over thirty years' service under heavy traffic, trebling their ordinary life, while there are numerous instances in which the oak has doubled its life, and the hemlock has given from five to six times its usual service.

The durability of well-treated ties is well established in this country by considerable experience on various railways. In England, France, and Germany the experience is ample, the ties lasting there longer than we can expect them to last here, from the fact that chairs are generally used to hold the rail and distribute the weight to a greater area of wood than is the case with the base of our rails; and, besides, the tonnage per car-wheel is less than ours. It is our freight-cars, with limited spring action, which cause a large portion of the abrasion of the ties. The economy would be great that would result to the railways by prolonging the life of their ties by treatment; this fact was realized long since, but in putting it into practice the information and experience were not sufficient to enable their engineers to secure the anticipated beneficial results. In fact, much of the treatment hastened the decay of the ties and timber, or, when overdone, destroyed their strength. This need be the case no longer, for the study of many of these failures has given much of the information needed, and the experience in treating wood is now extensive. The cheaper grades, such as the beeches, maples, birches, elms, and hemlocks, having a structure sufficient to sustain a heavy traffic, can be treated and substituted at less expense than the first cost of untreated white oak or yellow pine, and have a greater durability. This would effect an immediate-economy in the renewal of ties.

It would be decided economy to treat the higher-priced ties, so as to double their durability. A general example is given of a mile of track on a trunk line, where 2,800 ties are used per mile: This year the ties cost fifty-five cents apiece; to lay them in the track costs fifteen cents more, and their average life will be seven years. To treat these ties