PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 519 



bonic acid, or creosote, has been found to be of the least service 

 in preserving wood. It costs seven cents per cubic foot for pre- 

 serving wood, and there being three cubic feet of timber in each 

 sleeper, the cost for labor, along with the expense of creosoting, 

 will amount to twenty-one cents. 



The Chairman said it would cost fifty cents to replace each 

 sleeper. Anything that will give a permanency of three times 

 the length of time they exist now will create a saving which will 

 be incalculable. 



Mr. Veeder said that if the locust tree could be made to grow 

 in the West, where there was such a fertile soil and a great num- 

 ber of railways, it would be of great economic value to railway 

 companies. Chestnut wood, although porous, was better than 

 any other, except cedar and locust. 



The Chairman said that hickory wood was the hardest there 

 was, but that it decayed the most rapidly. 



Mr. Si-evens stated that the specific gravity of the oak was 

 greater than any other. Air can be forced through the chesnut 

 by the human lung. 



The Chairman. — If you cut the ceil walls of the tree 3'ou will 

 find them very compact. 



Mr. Stevens said, in answer to a question of Mr. Seely, that 

 some living trees commence to decay from the center, and others 

 from the outer surface. The pith is disseminated all through 

 the tree. 



The Chairman. — Have you observed that it is more minutely 

 disseminated through the white oak than any other ? 



Mr. Stevens. — In some cases it is microscopical. In Wayne 

 county there was a tree found lately, which, on examination of 

 some blaze marks found in the wood, with several annual rings 

 of wood over them, proved that it was in existence at the time 

 the Spaniards landed in Texas. 



The Chairman inquired whether there was a greater tendency 

 to decay in trees that wei-e poorly supplied with pith, in compa- 

 rison with those which were well supplied. A tree of button 

 wood was in existence near the salt mines, the circumference of 

 which was nearly 30 feet, while only about three inches of the 

 shell remained. 



Mr. Johnson said he had certificates extending back 20 years 

 in favor of creosoting. Timber thus used loses some of its flexi- 

 bility ; it hardens wood, and prevents abrasion in soft wood. 



