CONCLUSION. 
By Howard Constable, C. E. 
The practicability and economy of wood-preservation have been 
brought in question often, because the processes have been conducted 
by dishonest contractors or have been based upon some unwarrantable 
theory rather than upon any scientific principles. Nevertheless many 
successes have been achieved, and improvements have been made in 
the details of treatment and in mechanical contrivances to meet the 
conditions peculiar to this country. The follwing table * of experiments, 
in addition to those mentioned by Col. Flad, is certainly encouraging. 
Both here and abroad the durability of wharf and other timber sub- 
ject to severe exposure has been and can be at least doubled. The 
durability of piles and other timber subject to the attacks of the sea- 
worm Teredo can be prolonged three or four times. The possible econ- 
omy resulting from the use of treated Hemlock ties, instead of White 
Oak in their natural condition, has been estimated by Mr. O. Chanute 
as follows : For a road with about 2,000 miles of track, containing about 
5,000,000 ties, $250,000 in first cost every twelve years, and 8250,000 
each year in the average charge for renewal of ties. Some moderate- 
sized roads use as many as 400,000 ties a year, and have to get from 
one-quarter to one-half of them from other territory than their own, 
which, of course, results in the railroads putting great obstructions to 
the shipping of ties out of their own region, and necessitates going to 
great distances for the extra supply. 
A few are familiar with all these facts, but the majority, and the 
economists or business men, frequently realize them only partially, and 
d > not appreciate the importance of the subject to themselves. We 
sh ill be accomplishing much if we aid in giving these persons a coin- 
jjrehensive and clear idea of it in its general bearings. 
One of the first things to be clearly understood is that the field of 
wood-preservation is a very large one, embodying many natural and 
artificial conditions somewhat different in each particular locality and 
case. Every one cannot preserve wood with advantage. It cannot yet 
be done cheaply enough for ties on a new road in a heavily wooded 
district, any more than we could use stone for depots in such a region. 
* See p. 98. 
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