-'86 PRACTICAL ARBORICULTURE 



QUALITY ESSENTIALS FOR RAILWAY SLEEPERS. 



Railway officials and investors are now giving much attention to the 

 subject of suitable materials available for cross-ties or sleepers, whether, they 

 shall be made of metal, concrete, or a combination of several materials, or 

 of wood, and if the latter, what species of trees are best adapted for the pur- 

 pose, and which kinds may be grown within the limit of time when the present 

 supply shall have become exhausted. These are subjects to which attention is now 

 riveted. 



There is a great danger in going to extremes with various tests, and in 

 placing too great stress upon immaterial points, and thus losing sight of the 

 more essential qualities. 



\\ e desire to point out some prominent features which should receive 

 consideration by engineers, in forming a scale of tests, and we place these 

 in the following order: 



(1) Durability. 



(2) Elasticity. 



(3) Transverse strength. 



(4) Cost of production. 



(5) Time required for production. 



(6) Spike-holding quality, or density. 



DURABILITY. 



. In considering the qualification of metals it should not be overlooked 

 that oxidization, electrolysis, danger from breakage, especially under frost 

 conditions, tend to reduce the value and longevity of sleepers, while in the 

 use of cement concrete and combinations in which this material is used, the 

 effect of frost and impact of heavy trains and of disintegration must be kept 

 in view. 



In the use of wooden sleepers, the experience of railway officials, actual 

 long-term trials by many railways, and the credible statements of those who 

 have had long and practical experience in the use of certain woods, are 

 entitled to large consideration. 



In the chemical treatment of inferior woods, the cost of impregnation 

 and of transportation to and from the plant must be considered together 

 and if a timber possesses equal or greater durability without the necessity 

 for such artificial chemical treatment, it should receive due credit for this 

 valuable quality. 



