No. 124. j 149 



In all countries, trees extend their branches most against the direc- 

 tion of the prevailing winds. The general direction of branches in 

 this country is towards the northwest. Trees growing on an undu- 

 lating surface, adapt their lower branches somewhat to the undu- 

 lation. 



Chairman. — Green wood lessens by drying ; will it swell again by 

 moisture to its original dimensions ? 



Mr. Brown. — Warm water will swell it beyond. 



Mr. Glen. — When cut, the capillary attraction is at its strongest 

 force. Seasoning destroys this property of wood. It must be sub- 

 jected to wet for a long time, in order to regain its size ; boiling 

 water may do it. 



Pine being resinous, might be usefully impregnated with additional 

 resin. Hard woods cannot be well impregnated. 



Chairman. — Wood retains its length so well, that seasoned wood 

 formed into pendulum rods have been preferred to rods of metal. 

 Some wooden structures, ships particularly, have appeared to length- 

 en, but it appears to be owing to the interposition of matter, between 

 the wood ends, forcing them apart. 



Mr. Brown. — I examined some railing on a bridge. There were 

 two rails of about 25 feet long each, spliced together and spiked. 

 They were made of green white oak. I adjusted the length by a 

 chain, and in the following spring I found that there had been a 

 shrinkage oi half an inch in 10 feet. 



Mr. Glen. — Wood when perfectly frozen and fitted in work, never 

 shrinks, it is believed. 



Chairman. — Wood after being turned in a lathe, sometime after, 

 becomes oval! Why 1 



Mr. Brown. — Owing to the different densities of its rings. 



Mr. Meigs. — In our latitude, the southern rings of trees are thicker 

 than the northern. The heart is ecceiitric. 



Mr. Brown. — There is a difficulty in procuring good levelling 

 rods. Mahogany is good ; I have tried many kinds of wood and 

 have found the yellow birch to be best. 



Chairman. — The British reject the use of ivory scales. They pre- 

 fer box to lance wood. 



Wood and its Application to the Mechanic Arts. 



Chairman. — What are the uses of the Acacia tree 1 



Mr. Brown. — We have not this tree ; the true Acacia. 



Chairman. — The keel of|the Gibraltar, a ship of the line, was 

 made of Acacia, and after running from 1751 to 1843, the keel was 

 taken for use as a keel in a new vessel. It was not in the least in- 

 jured by worms. 



Mr. Brown. — Hickory is much less liable than many other woodg 

 to the attack of the salt water worm. Hemlock, with the bark on is 

 durable for docks. The cabbage tree of the south is valuable for 

 docks on account of its gieat durability. The worms are far more 



