34 
degree of weakness that was altogether dangerous within. He thinks that this proc- 
ess has a tendency to produce dry-rot, especially of Pine or soft-wood. 
"It would, however, he unfair to draw conclusions from American experience, and 
perhaps it would he just to attribute some, at least, of the failures that have fol- 
lowed to the inexperience of workmen and to the superficial and imperfect manner 
in which these processes have been applied." 
The last sentence explains the matter. The fault was not in the an- 
tiseptic but in the manner of its application ; the heart- wood was not 
impregnated with a sufficient quantity to protect it from the fungi. 
STRUCTURE OF THE WOODS UNDER CONSIDERATION. 
In the following pages will be considered the structure and nature of 
some timbers with reference to their use as railway ties, and their 
special requirements in regard to preserving processes ; namely those 
which form the bulk of our wood supply for railway purposes — White 
Oak, Chestnut, Cedar, Yellow Pine, Hemlock, and Tamarack or Larch. 
The oak and chestnut belong to the Angiosperms, and the cedar, yel- 
low pine, hemlock, and tamarack, to the Gymnosperms, all of the latter 
having the general characteristics and structure of the Ooniferae, but 
differing from each other in detail, In the first two the cell- structure 
is entirely unlike that of the last four, being far more complex and 
highly differentiated, the inner portion of each annual layer having 
from one to three concentric rows of large ducts, while smaller ones are 
distributed through the entire layer. 
All these trees are Exogens or outside growers, and if we look at a 
transverse section of any of them of the natural size we see it is com- 
posed of a series of annual rings, each representing a distinct period of 
active growth, generally only one ring forming each season, but often 
varying in thickness. For instance, in the White Oak ( Quercus alba. L.) 
a layer of a poor season's growth may not have the full number of the 
hard, dense fibers which give hardness to the wood. To some extent 
this is true also of the chestnut. In the other woods under considera- 
tion each layer will have more nearly its proper proportion of the dif- 
ferent fibers, though the layer may be thin. Through each annual ring- 
pass the medullary rays, which extend from the bark to the pith, and if 
a small section be magnified the general characteristics of the entire 
layer are seen ; if the section be taken from the sap-wood the structure 
is not so complete as in heart- wood, and the cell contents are not the 
same. In the mechanical destruction of ties the ease or difficulty with 
which the rings separate has much to do with the wearing capacity and 
consequent durability of the ties. This feature differs in all the woods 
under consideration, and will be specifically treated for each one. 
PHOTOMICROGRAPHS OF THE MAGNIFIED STRUCTURE OF THE WOODS. 
The photomicrographs accompanying this report are all enlarged 
to one scale, namely, 100 diameters, and by employing the metric scale 
in making a measurement, and dividing by 100, the natural size of 
