290 PRACTICAL ARBORICULTURE 



SPIKE-HOLDING QUALITY. 



Some engineers who have had experience with chestnut ties are fearful 

 of all woods which are not so dense as white oak, and go to the extreme of 

 testing woods by their ability to hold a spike. Yet those very dense woods 

 which cling with tenacity to nails or spikes which have been forced into 

 their body so that they will break before they can be withdrawn, are not 

 the best timbers for railway sleepers. 



The use of tie-plates not only adds to the durability of sleepers, but 

 greatly increases the capacity of timbers to hold spikes, or rather decreases 

 the tendency of springing rails to withdraw the fastenings. 



In removing rails for repair of track or change of line, it is of importance 

 that spikes may be withdrawn by workmen, and that they may be quickly 

 driven after the change has been made. Very dense woods, which require 

 to be bored before spikes may be driven, are very objectionable on this 

 account, as well as being of extremely slow growth, taking a long period for 

 maturity. 



Timbers of moderate hardness are far superior to those of extreme 

 density. The same may be said of rosewood, lignum vitae, and other tropic 

 woods which are used to some extent. 



DEDUCTIONS. 



The first qualification, essential to premanent railway sleepers, is dura- 

 bility. A material which requires renewing within four or five years is very 

 expensive, no matter what the original cost. 



Of wood, no timber has lasted so long in the tracks as catalpa, which, 

 after thirty-two years, ten years of which were under heavy traffic, still 

 remain sound. 



It is not so much a question for engineers to discuss as to what par- 

 ticular timber will be demanded, as what it is possible to procure. 



Railways must have ties, and brave them speedily and in vast quantities. 



Catalpa can be grown to supply sleepers in sixteen years, provided the 

 trees be planted and cared for. Time wasted in frivolous discussions and 

 scientific tests for non-essentials only delays the practical work of planting. 

 and of course prolongs the period of temporary expedients, a search for woods 

 of short life in the track, and expensive treating plant for inferior woods. 



The evidences furnished at the St. Louis World's Fair in the catalpa 

 exhibit were sufficient to prove that catalpa possesses every requisite for use 

 as sleepers, and that many thousands of ties have been in practical service 

 from the time of the earliest railway building in Indiana, Illinois and Mis- 

 souri, and that the wood was satisfactory for the purpose and so recognized 

 by many of the best engineers of America ; while at the same time being 

 suited for all the purposes of the builder, in carpentry, for furniture requiring the 

 highest polish, for mine timbers, and, as well, for pulp and paper. 



