266 THE YEAR-BOOK OF AGRICULTURE. 



Government, at Norfolk. The experiments were made under the direction of the Navy De- 

 partment, with a view of determining the proper time for cutting timber, and the best mode 

 of curing it or securing it from dry-rot. These are confined to the three principal kinds of 

 ship-timber, viz., live oak, white oak, and yellow pine, and will be of incalculable benefit to 

 the naval and mechanical interests of the United States. '? When we remember that there is 

 no table of specific gravity that is at all reliable for any meridian in North America, and that 

 our mechanics have been making their calculations from tables of specific gmvity found in 

 European works, we shall begin to approximate a conception of its value. A location in the 

 timber districts of this wooded country for practical purposes will satisfy the most incre- 

 dulous that little is known about the productions of the American forest. 



The following is the order of the experiments followed by Mr. Jarvis: On the 13th of 

 September he received, in twelve-feet lengths, the butts of ten trees of live oak, and an 

 equal number of white oak and yellow pine ; five of each kind were worked square at the 

 place where cut, and the remaining five were brought round with the bark on. After their 

 arrival, they were subdivided into three-feet lengths ; the square pieces were from twelve to 

 fifteen inches square ; the round pieces in bark from twelve to fifteen inches in diameter. 

 The specific gravity of each piece was at once obtained, and then they were located as follows : 

 Four pieces of the squared live oak, and four pieces of the round live oak in bark, were placed 

 in tanks under cover, where were solutions of corrosive sublimate, alum, copperas, and coal tar, 

 and the same number of white oak and yellow pine, amounting in all to twenty-four pieces 

 of the varieties of ship-timber ; one-half of which were square pieces, the other half round 

 and in bark. These live oak, white oak, and yellow pine pieces were kept in the tank, sub- 

 merged one month, at the expiration of which time they were distributed as follows under 

 cover in open air, planted as posts, and laid as railroad sills. There is a suitable number of 

 the pieces which have not been prepared, also under cover in open air, planted as posts, and 

 laid as railroad sills. A proportion of the pieces are square, and some round, and water- 

 seasoned for six months. After being removed from the water, two pieces are made of one, 

 and one kept under cover, the other in open air. The pieces which have not been in the 

 solution are the test-pieces ; and among these pieces Mr. Jarvis has fitted some together, 

 wood and wood, except having between them tarred paper coated with charcoal-dust. A few 

 years will prove, by ocular demonstration, which of the solutions, substances, or water, will 

 make timber most durable. The pieces which have had no preparation on them, and are 

 kept under cover, are weighed each month, to observe the amount of juices or moisture lost 

 by evaporation in one month and in one year. The object in weighing or obtaining the 

 specific gravity each month in the year is that he may be able to determine the best time for 

 cutting ship-timber, or whether it is of any material consequence ; and, by testing the weight 

 of the same kinds of timber, in connection with its durability, thus set this matter at rest. 

 The timber used for these experiments is thus described : the live and white oak are of ex- 

 cellent quality, and felled purposely, with a few exceptions, for these experiments. The 

 yellow pine is not as good as is used in the navy ; its specific gravity will not prove the fact. 

 The very best of yellow pine is not of the greatest density. Pitch-pine is not as good for 

 decks or deck-frames as other fine-grained pines from the South. The very best yellow pine 

 timber is that in which the even fineness of the grain is continued to the centre or pith of 

 the tree. By careful observation, much information that is valuable may be obtained from 

 the table of specific gravity: notwithstanding the thickness of the bark of the yellow pine, 

 and its lightness, (the specific gravity differing not materially from that of cork,) we find 

 that the pine timber in bark weighs much more than the square timber. This, to the casual 

 observer, would hardly seem possible ; the man unacquainted with the nature of yellow pine 

 sap-wood would be likely to doubt the correctness of the table. But such is the nature of 

 the exterior coating immediately under the bark of yellow pine, that we cannot find a more 

 analogous substance than that of sponge ; its retentive properties are very similar, and the 

 turpentine with which this sap-wood is saturated is the cause of its increased specific gravity 

 above that of the squared timber, when covered with bark. The thinner the sap-wood, the 

 less the specific gravity. There is an error in the prevailing opinion in relation to the dura- 

 bility of yellow pine timber. Our government has become a heavy stockholder in this pre- 



