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AB, 2 Chains which I fet off from A to B, the place of my fecond Station, by the help of iny Scale and Compaffes.
Secondly, I plant my Table upon the point B, and laying my Index upon the Line ZX, I turn the Table abour, till through the fights I behold my firft Station at A, then I Screw the Table faft to the staff; afterwards moving my Index upon the point B, I direct the fights to G, drawing the ob fcure Line BG, containing 1 Chain 75, then again 1 direct the Index to the Angle H, and find it diftant from my Station 1 Chain 72; and thus turning my Index about upon the point B, I draw obfcure Lines to the other Angles as I did before, and meafuring their respective diftances with my Chain, I prick down the points I, K, L, upon my Paper, ever obferving to take off with my Compaffes upon the Scale the exact Quartity of Chains and Links, measured with the Chain.
Laftly, (The feveral prints or Angles of the Field, as CDEFGHIKLM, being found out, and mark'd upon my Paper,) I draw the Boundary Lines from point to point, which will reprefent the true Plot of the Field, to be Measured.
To take the Plot of a Field removed from you; at two Stations, when you are not permitted to come within the fame.
Fig. 95. It often happeneth that you are to measure a Field, and cannot, either for Water, Moorish Ground, or danger of Suit, enter into it. Suppofe the Field is CDEFG, I make Choice of two conveni nt Stations without it, as A and B, from each of which I can fee all the Angles of the Field; and having planted my Table at A, I place the Edge of my Index thereupon, and direct to all the Angles of the Field refpectively, drawing Lines with the point of my Compaffes, as AG, AE, AF, AD, AC, AH. Then my Table remaining fir'd, I direct the Index towards B, and having drawn out my Stationary Line, I measure the diftance thereof in the Field, and place it on the Paper from A to B, then planting the Table at B, place your Index upon the Stationary Line B, and then move the Table, till through the fights you be hold your Station at A; which being effected, direct your Index to all the feveral Angles of the Fie'd, as you did before at A, and the interfections of these Lines, will give the points C, D, E, F, G, H, from which draw the Lines CD, DE, EF, FG, GH, and HC, and you will have the true Plot, and Proportion of the Field.
To Survey Wood-lands by the plain Table.
In very irregular Grounds where you can make long Stations, you cannot fee all the Angles from each Station; but in going on your Stationary Line, all the little corners in the Hedges may be feen; therefore, that you may Plot all the Angles as you measure on your Stationary Lines, obferve this General Rule, viz.
A General Rule.
In going on your Stationary Line, mark where an Angle falls in a Right-Angle to your Stationary Line, there plant the Table, laying your Index upon the Stationary Line, and turning your Table upon the Head of your Staff, till you can fee either the Station you came from, or that you are going to, (for You must always obferve to measure in a freight Line from Station to Station,) there fcrew it faft; then obferve how far you have meafured on your Stationary Line, which diftance take from your Scale, and place from your laft Stationary Line, there make a prick with your Compaffes point, and there take the Angle,
Fig. 96. Suppofing ABCDEFGHIKLM NOP, to be a great Pool or Wooi: Though there be Fifteen Angles, I plant my Table only five times, viz. at EFH and M, and upon the dry Lines AE, FH, HM, and MA, I raife their Perpendiculars in due. places, (according to Measure) and also of a right heighth: By which and my five Stationary Angles, I draw the bounding Lines of the Plot, excluding all the Triangles as foreign to it, they being no refemblances of any part of the Pool, but of Land adjacent. That if by reafon of troublefome Brufh-wood, Gorfe or Bogs, &c. I could not have meafured clofe to the fides E-F HI, or LM, it would be the fame thing if I went parallel to them. And this is a fhift that the Practical Suveryors will oft be put to make ufe of.
Now before I pafs to further Varieties let my Reader take notice of thefe following things.
1. That it is the quickeft way to measure, firft from the Inftrument to the firft Angle, and then back from the fecond Angle to the Inftrument, and fo the reft in order ; Atill one from the Inftrument, and the other to it.
2. In all working by the plain Table, you must have a care that the Inftrument be not moved out of its due place, till you have finished the work at the prefent Station, for which purpose caft your Eye now and then upon your Needle, obferving whether it hangs directly over the fame point you fet it at when you began your work, and to rectify your Inftrument if you fee caufe. But becaufe all Inftruments have not Needles, make ufe of the following help.
When you have planted your Infitument, and made a prick on your Paper, reprefenting your Station, fet the Edge of the Index to it and turning it foftly about till you find fome remarkable thing upon one fide of the Clofe, and another on the oppofite fide as you look through the fights of your Index,and draw a remarkable Line quite over your Paper; then if you fufpect that by any accident the Inftrument is removed, you may eafily try and rectify it, by applying the Index to the fame line, and making ufe of fore-fights and back-fights again, upon the fame marks which you before obferved upon the oppofite fides of the Clofe. And this is a very good way when you plant your Inftrument in the middle of the Field