OF FOREST-TREES. 



317 



these hard knots beyond a black scorching, although, being laid on cH. XXIf. 

 heaps, they are apt enough to burn. It is of these knots they make "'^-*~v^*«-> 

 their tar in New England and the country adjacent, whilst they are well 

 impregnated with that terebinthine and resinous matter, which, like a 

 balsam, preserves them so long from putrefraction. The rest of the tree 

 does indeed contain the like terebinthine sap, as appears, upon any slight 

 incision of the bark on the stem or boughs, by a small crystalline pearl 

 which will sweat out ; but this, for being more watery and indigested, 

 by reason of the porosity of the wood, which exposes it to the impressions 

 of the air and wet, renders the tree more obnoxious ; especially if it lie 

 prostrate with the bark on, which is a receptacle for a certain intercuta- 

 neous worm that accelerates its decay. They are the knots then alone 

 which the tar-makers amass in heaps, carrying them in carts to some con- 

 venient place not far off, where finding clay or loam fit for their turn, 

 they lay an hearth of such ordinary stone as they have at hand : This 

 they build to such a height from the level of the ground, that a vessel 

 may stand a little lower than the hearth to receive the tar as it runs out. 

 But first, the hearth is made wide, according to the quantity of knots to 

 be set at once, and that with a very smooth floor of clay, yet somewhat 

 descending, or dripping, from the extreme parts to the middle, and thence 

 towards one of the sides, where a gullet is left for the tar to run out at. 

 The earth thus finished, they pile the knots one upon another, after the 

 very same manner as our colliers do their wood for charcoal, and of a 

 height proportionable to the breadth of the hearth, and then cover them 

 over with a coat of loam, or clay, which is the best, or, in defect of those, 

 with the best and most tenacious earth the place will afford, leaving only 

 a small spiracle at the top, whereat to put the fire in, and making some 

 little holes round about, at several heights, for the admission of so much 

 air as is requisite to keep it burning, and to regulate the fire by opening 

 and stopping them at pleasure. The process is almost the same with 

 that of making charcoal ; for when it is well on fire, the middle hole 

 is also stopped, and the rest of the registers so governed as the knots 

 may keep burning, and not be suffocated with too much smoke, whilst 

 all being now thorough-heated, the tar runs down to the hearth, together 

 with some of the more watery sap, which hasting from all parts towards 

 the middle, is conveyed by the fore-mentioned gutter into the barrel or 

 vessel placed to receive it. Thus the whole art of tar-making is no other 

 than a kind of rude distillation per descensum, and might therefore be as 



