1904 



FORESTRY AND IRRIGATION 



475 



has long been in general use abroad. 

 With proper methods it can be made 

 entirely successful, and impregnation 

 with creosote, zinc chlorid, or other an- 

 tiseptic substances allows the use of 

 many woods hitherto passed oveV, as 

 well as of sawed ties, sapwood, and 

 dead timber. Preservative treatment 

 can make a beech or red oak or pine 

 tie outlast a white oak tie. But the 

 wearing away of the softer fibers of 

 these woods under the rail and around 

 the spike raises a new set of problems. 

 Even with cheap treatment practi- 

 cable, which insures against the de- 

 struction of the tie in the ground by 

 decay, it is neither economical nor safe 

 to equip a road with such ties unless 

 mechanical devices can be found which 

 will prevent rapid wear. Ties chemic- 

 ally treated resist decay, but the softer 

 woods can not withstand wear of the 

 rails nor hold the spikes under the 

 heavy traffic of American roads. 



This is true not only of ties upon 

 which the rails rest directly, but also 

 where the old forms of steel plates in- 

 serted between rail and tie are used. 

 Indeed, the thin plates with prongs or 

 spines and flanges, hitherto generally 

 used in the United States, appear to 

 hasten rather than retard wear of the 

 tie. With accompanying screw-spikes, 

 which hold the rail firmly to the tie, 

 several forms of plates can be intro- 

 duced successfully. Wooden tie-plates 

 can be used, which, when worn out, are 

 easily replaced. 



The functions of spikes are, first, to 

 hold the ties to the rails, and, second, to 

 prevent the rails from spreading. Nail 

 spikes are still used for this purpose in 

 this country. In driving a spike into a 



white-oak tie the strong and elastic fiber 

 of the wood is bent downward, main- 

 taining a close contact, so that powerful 

 resistance is offered to its withdrawal. 

 When driven into such woods as hem- 

 lock and western yellow, lodgepole, lob- 

 lolly, or shortleaf pine, the fibers of the 

 wood are crushed and broken. As a re- 

 sult the spikes do not hold with suffi- 

 cient firmness to withstand the undula- 

 tory motion of the rail nor the lateral 

 pressure against them. They become 

 loosened, and the constant friction en- 

 larges the spike-hole until water collects 

 in it and decay begins. The spike must 

 soon be driven in a new place, and this 

 constant respiking rapidly ruins the tie. 

 Even if the tie has been treated with a 

 solution like zinc chlorid, the water will 

 leach out the salt, so that decay-produc- 

 ing factors begin their work. The solu- 

 tion of this difficulty is achieved by the 

 use of a screw spike. In the soft woods 

 screw spikes will resist nearly three 

 times as great a strain as nail spikes. 

 If inserted in a screw dowel of hard 

 wood, the power of the screw spike is 

 still greater. A key operated by two men, 

 a hand-power screw-spike-driving ma- 

 chine, or a machine with electric power 

 may be employed to insert screw spikes. 

 Arrangements are being made for the 

 extensive introduction of these appli- 

 ances, the need of which has developed 

 so conspicuously in the brief experience 

 with treated timbers. If in the main- 

 tenance of a stable track, so indispens- 

 able for the safety of trains moving at a 

 high rate of speed, the proposed equip- 

 ment fulfills the promise of experimental 

 tests, an important step in the better 

 utilization of our forest resources will 

 have been made. 



