The gentlemans recreation in two parts : the first being an encyclopedy of the arts and sciences ... the second part treats of horsmanship, hawking, hunting, fowling, fishing, and agriculture : with a short treatise of cock-fighting ... : all which are collected from the most authentick authors, and the many gross errors therein corrected, with great enlargements ... : and for the better explanation thereof, great variety of useful sculptures, as nets, traps, engines, &c. are added for the taking of beasts, fowl and fish : not hitherto published by any : the whole illustrated with about an hundred ornamental and useful sculptures engraven in copper, relating to the several subjects.

CHAP. XVIII.

To protract, or lay down Mounta∣nous, and uneven Grounds, with the best way to find the Area, or Content of such Irregulars. [ 10]

LEt A, B, C, D, E, F, G, be a Mountanous Piece of Ground to be measured; First, place your Instrument at A, and direct your Sights to B; then measure the Line A, B, draw the same by the Side of the Ruler upon the Ta∣ble; then in regard that from B, to C, there is an Ascent, find the Horizontal Line thereof, and draw it upon your Table, reckoning thereon the length of the Hypothenusal Line; then measure [ 20] round the Field according to former Directions, and having the Figure thereof upon your Table, reduce it into Trapeziums, as A, B, E, G, and B, C, D, E, and the Triangle G, E, F; then from the Angles A, C, E, F, fall the Perpendiculars.

Now by reason there are many Hills and Val∣leys all over the Field, you must measure with your Chain in the Field over Hill and Dale from B, to D, and to the Line B, D, set the number of Perches as you find them by measuring, which [ 30] will be much longer than the streight Line B, D. measured on the Scale; then by the help of your Instrument find the Point H, in the Line B, D, and measure with your Chain from C, to H, over Hill [ 40] and Dale, as afore∣said, and to the Perpendicular C, H, set the num∣ber, as you find it by the Chain; then likewise find the Perpendicular I, E, and likewise mea∣sure that with your Chain; all which Lines in respect of the Hills and Valleys will be found much longer than if measured by your Scale: Then by the Measured Lines BD, CH, and IE, cast up the contents of the Trapezium B, C, D, E, and in this manner cast up the content of the [ 50] Trapezium A, B, E, G, and the Triangle G, E, F; and this is the exactest way to be prescribed from the mensuration of uneven Grounds, which be∣ing carefully peformed, will not much vary of the true Content. And to distinguish these from other Grounds, Shadow them off in your Plot with Hills and Valleys, lest any should mea∣sure your Plot by your Scale, and find your work to differ. [ 60]

[illustration]