228 ENGINEERING ON THE FARM 



Investigations carried on at the Ohio Agricultural Experi- 

 ment Station developed the following information with 

 regard to wood posts. Large posts usually last longer than 

 small ones of the same wood. It makes little difference 

 which end is put in the ground except that the larger or 

 sounder end should have the preference. In stiff clay soil 

 posts decay principally just beneath the top of the ground. 

 In porous sandy or gravel soil they usually rot from the 

 top of the soil down. Seasoning does not seem to have any 

 marked effect on durability unless followed by some other 

 treatment. Timber that grows rapidly and in the open is 

 not so good as the same variety grown in the woods. Though 

 it has not been absolutely proved, there is some evidence 

 that just when the trees begin to grow in the early spring 

 is not a good time to cut posts. The wood at the center of 

 the tree is not so good as that just inside the sapwood. 

 This is especially true of locust, cedar, and hardy catalpa. 

 The quality of the wood or the condition of the wood fiber 

 of the post is a very important factor in its ability to with- 

 stand decay. The poorer quality of posts and defective 

 portions in otherwise good posts are usually somewhat darker 

 than the normal color, especially near the center of the tree. 



Preservative treatment. The life of a wood post can be 

 prolonged by methods of treatment which will prevent the 

 growth of fungi. A waterproof coating may be applied to 

 the post to exclude moisture or a coating which is in itself 

 poisonous. Either of these will tend to delay the action of 

 rotting by interfering with the development of the fungi. 

 Another method is to char the lower part of the post from 

 the bottom to a point which will be about twelve inches 

 above the surface. One way of doing this is to hold the lower 

 end of the post over a hot fire, which will form a coating of 

 carbon over the surface, or, more satisfactorily, to dip the 

 end in crude petroleum and then burn off the oil. This 

 drives the hot oil into the post, and, with the charred coat- 

 ing, prevents decay. Another method is to dip the seasoned 



