246 S Y L V A BOOK ii 



crystalline pearl which will sweat out ; but this, for 

 being more watery and undigested, by reason of the 

 porosity of the wood, which exposes it to the impress- 

 ions of the air and wet, renders the tree more obnox- 

 ious ; especially, if it lie prostrate with the bark on, 

 which is a receptacle for a certain intercutaneous 

 worm, that accelerates its decay. They are the knots 

 then alone, which the tar-makers amass in heaps, 

 carrying them in carts to some convenient 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 an 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, accord- 

 ing 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 extream parts to 

 the middle, and thence towards one of the sides, 

 where a gullet is left for the tar to run out at. The 

 hearth thus finish'd, they pile the knots one upon 

 another, after the very same manner as our colliers 

 do their wood for charcoal ; and of a height pro- 

 portionable to the breadth of the hearth ; and then 

 cover them over with a coat of loam, or clay, (which 

 is 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, as will appear in due place ; for, when it is 



