HE last thing I purposed to speak of, is, Those several Qualities of Timber or of Trunks, by which they are fitted for Mechanical Use. As Hardness, Softness, Fastness, Clevesomeness, Toughness, Brittleness, Durableness, or any of the same Qualities compounded. The Visible Causes whereof are observable, Partly, in the Structure of the several Parts; sc. the Insertions, Sap-Vessels and Aer-Vessels; as to the Number, Size, or Position of any of them. And partly, in the Nature of the Parts; I mean such as is manifest to sense. According to our clear and distinct observing of all which Causes, we may understand, Wherefore any Wood is made use of for any certain purpose. And also, wherein fitly to apply it to further Use. In order to which, a compleat History of the Mechanical Uses of Vegetables would very much conduce. I shall for the present give some Instances.
2. §. AS First, some Woods are soft, as Deal, and Sallow. Yet from different Causes. Deal, from the great Porosity of the Wood it self, or the large Pores amongst the Sap-Vessels. But Sallow, from the great number of Aer-Vessels spread all over it. And therefore, though they are both soft, yet will not serve for the same purposes; Sallow being well wrought upon, which way soever you cut it: but Deal, especially the white Deal, if it be cut cross, it tears, and will never polish or work smooth.
3. §. Again, in Sallow, by the equal spreading of the Aer-Vessels, the Softness is equal or alike in all Parts. For which cause it maketh an excellent Coal for Painters Scribets. Because it doth not only make a light Stroak, but every where certain; and so doth not disturb the even Motion of the Hand. For the same cause, Shoemakers also make use of it for their Carving-boards. Because being every where equally soft, it turns not the edge of their Knives, Which Deal would presently do; because though very soft in some places, yet in others ’tis hard; that is to say, on the inner Verge of every annual Ring of Wood, where the old Sap-Vessels grow much more compact and close together.
4. §. AGAIN, some Woods are soft, but not fast; others are both, as Linn: its Softness, depending on the numerousness and equal spreading of the Aer-Vessels; its Fastness, on the closeness of the true Wood, and the shortness, and smallness of the Insertions. For which cause, it is of excellent use for many purposes; and particularly, for small Sculpture: such as may sometimes be seen for the Frames of Looking-Glasses, or of smaller Pictures in Water-Colours.
5. §. SOME Woods, again, are fast, and hard, as Elm. Its hardness depending upon the closeness of the Wood. Its fastness, Partly, upon the same cause; and partly, on the smalness of the Insertions; as also on the fewness of the Aer-Vessels in proportion with the Wood; and on the thwart and cross Position of many of them. Hence it is, that Elm, of all others, is the most Cross-grain’d Timber; that is, cleaveth so unevenly, to and fro, according to the cross Position of the said Vessels.
6. §. Hence also it cleaveth the most Difficultly. Even then, when it is without any Knots. For which reason it is always used, as best for the Hub of a great Wheel. As also for Water-Pipes, and for Pumps. Not because it is the most durable Wood; but because it will not split or crack, either in the working, or afterwards. For the very same reason, it is used for Coffins; that is, because, it will not split in working: not because it will endure longest under ground; for Pales are always made of Oak. So also the Ladles and Soles of a Mill-wheel are always made of Elm; as also the Keel of a Boat, sc. lest they should split: but the other Parts are made of Oak.
7. §. It may here also be noted, That the Planks commonly called Groaning-Boards, lately exposed, as a kind of Prodigy, to the view and hearing of many People, were of Elm. The Aer-Vessels of this Wood, being, though not more numerous, yet more ample, than in any other Timber. So that upon the application of the Red-hot-Iron, as was usual, and thereby the Rarifaction of the Aer and Watery Parts in the Timber; every Vessel became, as it were a little Wind-Pipe for their Expiration. And as a great many Drops falling together in a showr of Rain; so a great many of these Pipes playing together, might make a kind of big or groaning noyse.
8. §. AS Elm, of all Woods, is one of the fastest; So, on the contrary, of all hard Woods, Oak is the most Cleavesome, or splitteth the most easily. The cause whereof is, partly, the Largeness of the Insertions; and partly, the Diametral or Radiated Position of most of the Aer-Vessels: upon both which accounts, wherever a crack is once begun, ’tis easily continued throughout the Diameter of the Trunk.
9. §. AGAIN, some Woods are hard, fast, and tough. So is Ash, and especially Beech. Hard and fast, from some of the same Causes, as Elm. Tough not from the Structure, but from the Nature of the Parts; whose Principles are united in a more exact proportion. Wherefore London-Cars have the Rings of their Wheels of Beech; because it tears more difficulty than even Ash it self. Whence also for large Screws, there is no Wood like it. But for Small Screws, of about an Inch Diameter, Birch is the best; as being, though not so hard, yet more tough.
10. §. THE more Brittle a Wood is, ’tis likewise usually the more durable. So Oak, which, with respect to its hardness, is not a tough, but very brittle Wood, is almost as durable as any. Whereas Beech, Birch, and the like, although very tough; yet for Duration, are of no service; for there are no Woods will rot sooner: and therefore, though strong enough, yet unfit to make any Standing Parts of Building, or of Furniture; especially in wet and moist places. Because, these Woods, having a less proportion of Oyl, than there is in Oak; they are apter to imbibe the moisture even of a dank Aer; by which moisture, they either Rot, or breed Worms, which destroy them.
11. §. HENCE it is, that what we call the Heart of Timber, as it is more brittle, so also more durable; sc. Because more Oylie. So that which is called the Sap of Oak, is much more tough than the Heart, although the Heart be more durable. That is to say, the older the Wood is, the Watery Parts are the more evapourated, whilst the Oylie still remaine, as a kind of Tincture or Extract in the Wood. Even as we see, that the older Seeds of any one Kind, are more Oylie than those that are green and young. So that the Oylie or Rosinous Parts of the Sap, are a kind of Embalming to the Heart, or older Part of a Tree, securing it from the destructive impressions of the Aer. For which Cause it is, that Oak, Yew, 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 hence likewise we may understand the Cause of the Toughness of Flax: what we call Flax, being only the Sap-Vessels, or Lignous Fibres of the Barque. And generally, the Barque of any Tree, as of Willow (whereof are usually made a sort of Ropes) is very tough. The Vessels being here younger, and less Oylie than in the Wood. So likewise Hemp, is nothing else but the Sap-Vessels of the Barque of the Plant so called. And Scotch-Cloath, is only the Housewifery of the same Parts of the Barque of Nettle.
13. §. WHENCE it is very probable, that there are many other Plants, as well as the above named, whereof might be made good Tow. And of some, especially in some respects, better than of Flax it self. Because that even Hemp, although it will not make so fine a Staple, as Flax (for all our fine Hollands are made of Flax) yet Flax, which is but of the same fineness as Hemp, will never, by all the Art yet known, be made so white as Hemp is made. The Qualities therefore of the best Tow, that can be in Nature, are that the Staple be long, small, tough, and white. So that if in the Barque of any Plant, we can find these Qualities, or any of them, to excell; we may be sure, it will be of better use, in some respects, for the making of Cloath, or other purpose, than Flax it self.
14. §. I WILL conclude with one Instance more, and that is as to Grafting. The good and happy success whereof, doth certainly depend upon the suitableness or respondence betwixt the several Parts of the Stock and Cyon; as the Barque, Wood, and Pith; and that both as to the Number, Size, and Position of the said Parts, and of their several Pores or Vessels: according to the degrees whereof, the Conjunction (cæteris paribus) will be more or less prosperous. So that of all such Conjunctions as are found to be apt and taking, and which some have learned not without long Practice and Experience; another, only by comparing the Branches of Trees together, may with little trouble, and in much less time, inform himself. By the same means, some Conjunctions which seem to be strange, as Quince and Pear, White Thorn and Medlar, &c. do yet, by the respondence of their Parts, as well as by Experience, appear to be good. And there is no doubt, but that many Conjunctions not yet tryed, or not known to have been so, may upon the same ground, be tryed with good success.
15. §. The chief Use of Grafting and Inoculation, is, That they Accelerate the growth of Good Fruit. The Cause whereof, is the Knot, which is always made in the Conjunction. By means of which, all the Sap is strained, and so ascendeth up into the Graff or Bud, both Purer and in less Quantity; and is therefore better and sooner concocted. Hence, the smaller the Fruit of any Tree, though it be not the best, yet the Sap being there, in less Quantity, is the sooner ripe. On the contrary, where the Sap ascendeth too freely, it doth not only retard the growth of the Fruit, but produceth Barrenness; as is seen in those luxuriant Branches, where it runs all up to Leaves. Hence also Vines, by Bleeding, become more Fruitful: that is, by the Effusion of Part of the Sap, there is a more easier melioration of that which remains. Even as Phlebotomy doth oftentimes produce a more healthful and better Habit of our own Bodies. To conclude, the lessening the Quantity, and thereby the melioriation of the ascending Sap, by Knots, is Natures own contrivance; as is seen in Sugar-Cane, Corn, and other Plants.