Ex. I. A Hill (I fuppofe) may contain four equal Sides, which meet in a Point at the Top; but the Contents of those Four Sides can produce no more, either of Grain or Trees, than the plain Ground upon which the Hill stands, or has its Bafe; and yet by the Measure of the Sides, we find twice the Number of Acres, Roods, and Poles, which measures in the Base or Ground Plat.

Fig. I, is an equilateral Triangle, or a Body of three equal Sides: From A to B is One Hundred Yards; from A to C, One Hundred Yards; and from C to B, One Hundred Yards; fo that from B by A to C, meafures twice as much as from C to B, and therefore it is commonly fuppofed will produce double the quantity of Grain more than the Line C B: But as long as all Plants preserve their upright Method of Growth, we may be affured fuch Hilly Ground can bear no more Plants in Number than the Plan at the Bafe, as we may fee in Fig. II, which reprefents a Hill with a Row of Trees planted the Length of the Bafe, at certain Distances from A to C. In the fame Figure we may observe the fame Number of Trees planted from A by B to C, altho' the Line over the Hill meafures almoft double the Line from A to C.

Fig. III, gives an Example of Buildings upon a Hill, fhewing, that the two Sides of the Hill will only bear the fame Number of Houses that may ftand in the Line at the Bafe.

Fig. IV, is an Example of Rails, or Park-paling, over a Hill; whereby we may discover that tho' the Measure be near double by the Way over the Hill to the Line at the Bottom, yet the fame Number of Pales, of the fame Breadth, and at the fame Distance, ferves to inclose both.

C 4

I could

I could yet give many more Examples to prove that Hills, tho' they measure twice as much as the plain Ground they stand upon, yet the Produce of one can be no more than the other; and therefore in the purchafing of Land the Hills ought not to be fold or lett for more than Half their fuperficial Meafure, i. e. two Acres upon the Side of the Hills, to pay as much as one Acre upon the Plain, provided the Soil of both is equally rich, as it feems in this Cafe; tho' generally the hilly Ground is thought to be more inclining to Barrennefs than the lower Grounds.

But it remains that I fay fomething concerning the perpendicular Growth of the Stems of Trees, and other Plants, as it is neceffary to clear fome Doubts which may arife from the foregoing Obfervations, among thofe efpecially who are not very well acquainted with the manner of vegetatiye Growth.

The Point of the Stem, or Leader of every Trunk of a Tree, feeks the Air; and therefore in Woods where the Trees are thick fet, the whole Expenfe of Sap follows that upright Will of Nature, and the Trees in fuch a Station much taller and upright, than where one fingle grow Tree can have the Benefit of making collateral Branches.

It is neceffary that every Tree fhould grow upright or perpendicular to the Horizon, for the more eafy Support of it felf; for were Trees to incline naturally more to one Point than another, the Winds would more readily over-fet them; or where Trees were fully furnish'd in the Crown or Head with collateral Branches, their Weight would contribute by degrees to draw the Roots on one Side out of the Ground;

but

but especially when fuch Branches are loaded with Fruit, we frequently find the Neceffity of propping them, as may be obferv'd in many Orchards. We may indeed remark, that almost every Stem and every Root is first form'd in a bending manner under Ground, and yet all these Stems become ftrait and upright when they get above Ground, and meet the Air; and most Roots when they gather Strength, run as directly downward, and fhun the Air as much as poffible.

As Proofs of this Intent in Nature, for the upright Growth of Plants, we may observe that fome (which make their first Shoots horrizontally from a Wall, or the Side of a sharp Bank) turn up their Points or extreme Branches to the Air, as foon as they have taken faft Hold with their Roots. The Marricaria, Parietaria, and Antirrhinum, are fo many Examples. At first indeed, when their Stems are tender, their own Weight bends them towards the Earth; but in time, as they become stronger, altho' the Weight of the Heads of those Plants is then much greater, they turn their Shoots upwards, and at length grow upright almoft parallel with the Wall.

We may further remark how much this Intent of Nature is evidenced in the Growth of Peafe, Cucumbers, and fuch like Plants; as foon as they meet the Air they grow erect, till they attain the height of fix or eight Inches; and then wanting Strength to fupport their upright Intentions, recline, and by gentle degrees reach the Ground: But Nature in this Cafe gives them Means of Support, and to continue their perpendicular Vegetation by Clafpers or Tendrils; and if they have the Opportunity of catching

hold

hold of any Tree or Pole near them, they will then proceed in the firft Rules of natural Growth. But it is not worth while to give this Affiftance to every Pea we fet; we have Experiments enough in every Field, of their innate Defign of pointing their Branches upwards, when they have rested themselves upon the Earth fufficiently to fupport this fecond Attempt.

The Cucumber I find brings much fairer Fruit if it has the Advantage of climbing; and this Plant is not unworthy fuch Help; for if it is treated in that manner, 'tis grateful enough to 'reward our Care with a valuable Crop.

There is yet one more Obfervation which I think may be neceffary to fupport my Argument, and is what I find conftant in all Trees that have fuffer'd by rude Winds, or have been blown down. Monfieur Dodart, of the Royal Academy of Sciences at Paris, tells us, that one Day coming from Meudon, the Dauphin's Palace, thro' the Park to Chaville, he obferv'd on the Declenfion of the Hill feveral young Pine-Trees, which had been blown down by Storms at different Places; he remark'd that tho' the Fall of those Trees were very different with Regard to the Declension of the Hill, yet the extreme Branches (which had been the Leaders of the Stems when the Trees were growing) retook their natural perpendicular Growth, and turned upwards in fuch a manner as to form fharp Angles, which open'd more or lefs, as the fallen Stems on the feveral Declenfions of the Hill directed them to be upright: And he obferves likewise, that even the collateral Branches of Trees partake fo far of the first Design of the Mother-Stem, that whenever they are incommoded

commoded in their firft Defign of Growth, they tend upwards. But this laft Obfervation of Monfieur Dodart's I have not remark'd.

From thefe Remarks you may obferve, That Hills in their Measure contain only as much profitable Land as the Plan or Plat of Ground they stand upon and as a Proof of that,

All Vegetables or Plants have an erect Method of Growth.

As to the other part of your Letter, which relates to the Improvement of Heath-Land; the Remarks I have made on the feveral Beds of Earth, and the Specimens you sent me of them, has given me fome Thoughts, which I hope may be of Service to you in Husbandry.

In the first place it is neceffary to make the proper Diftinctions between the Hill and the Low Grounds; for the Vale has not only the Advantage in Measure, which I have already mention'd above, but has alfo the Benefit of Shelter, by Means of the Hills about it. A noble Lord lately told me, that when the Froft had deftroy'd all the forward Beans and Peafe on the Plains and Hills, that in a Valley in Suffex they remained unhurt: But this might happen as well by means of the Sea-Air, which prevents the Ravage of Frofts, as the Hills sheltering them from cutting Winds. In Dorfetfhire, Devonshire, and other Places near the Sea, I have often remark'd how much Plants were benefited by the Influence of the Vapour arifing from the neighbouring Sea; but chiefly those which were of the lower Race, which are properly call'd Herbs. In thefe Parts I obferve, that where the Hills fhelter fuch Herbs from the North and Eaft Winds, thofe Herbs come much more forward than where they have only the Advantage of Sea-Air,

But