For which 
ularly, for 
Frames of 
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s feine), 
ur 
y with the 
, Heei 
tati, 
tion ofthe 
Book HI. of Trunks. 
139 
their Expiration, And as a great many Drops falling together in a fhowr 
of Rain; fo a great many of thele Pipes playing together, might make 
a kind of big or groaning noyfe. 
8. 5. AS Elm, of all Woods, is one of the fafleft; So, on thé 
contrary, of all hard Woods, Oak is the moft Cleavefome, or Jplitterh 
the moft ea. The caufe whereof is, partly, the Largenefs of the 
Infertions 5 and partly, the Diametral or Radiated Pofition of molt of 
the Aer-effels: upon both which accounts, wherever a crack is once 
begun, ‘tis eafily continued throughout the Diameter of the Trunk, 
9. § AGAIN, fome Woods are hard, faft, and tough. So is 
Afb, and efpecially Beech. Hard and faft, from fome of the fameCau- 
fes, as Elm. Tough not from the strudéure, but from the Nature of the 
Parts; whofe Principles are united ina more exa& proportion. Where- 
fore London-Cars have the Rings of their Wheels of Beech; becaufe it 
tears more difficulty than even Ait {elf Whence alfo for large Screws, 
there is no Wood like it. But for Swal! Screws, of about an Inch Diames 
ter, Birch is the beft; as being, though not fo hard, yet more tough. 
10. $. THE more Brittle a Wood is, ‘tis likewife ufually the more 
durable. So Oak, , which, with refpe&t to its hardnefs, is not a tongh, but 
very brittle Wood, is almoft as durable as any. Whereas Beech, Birch, 
and the like, although very tough; yet for Duration, are of no fervice 5 
for there are no Woods will rot fooner : and therefore, though ftrong 
enough, yet unfit to make any Standing Parts of Building, or of Fur- 
viture; efpecially in wet and moilt places. Becaufe, thefe Woods, 
having alef proportion of Oyl, than there is in Oak 5 they are apter 
to imbibe the moifture even of a dank Aer 5 by which moifture, they 
either Rot, or breed Worms, which deftroy them. 
11. $. HENCE it is, that what we call the Heart of Tim- 
ber, as it is more brittle, fo alfo more durable; fe. Becaufe more 
Oylie, So that which is called the sap of Oak, is much more tongh than 
the Heart, although the Heart be more durable. That is to fay, the 
Older the Wood is, the Watery Parts are the more evapourated, whilft 
the Oyle ftill remaine, as a kind of Tinure or Extra£ in the Wood. 
Evenas we fee, that the older seeds of any one Kind, are more Oy- 
lie thanthofe that are green and young. So that the Oylie or Rofinous 
Parts of the Sap, are a kind of Embalming to the Heart, or older Part 
of a Tree, fecuring it from the deltruétive impreflions of the Aer, For 
which Caufe it is, that Oak, Tem, Cocus, Guajacum, &c. which are 
Oylie Woods, have always much Heart, whereas Birch, Alder, Beech, 
Maple, which are very Unoylie, have never any Heart, 
12. $. FROM hencelikewife we may underftand the Caufe of 
the Toughnefs of Flax: what we call Flax, being only the sap-Vefels, 
or Lignons Fibres of the Barque. And generally, the Barque of any 
Tree, as of Willow ( whereof are ufually made a fort of Ropes) is 
very tough. The Vefels being here younger, and lef Oylie than in the 
Wood. Solikewife Hemp, is nothing elfe but the Sap-Veffels of the 
Barque of the Plant fo called. And Scotch-Cloath, is only the Honfe: 
wifery of the fame Parts of the Barque of Nettle, 
13. $. WHENCE itis very probable, that there are many 
other Plants, as well as the above named, whereof might be made 
aod Tow. And of fome, efpcially in fome refpeéts, better than of 
lax itfelf. Becaufe that even Hemp, although it-will not make fü 
Aaa fine 
