« ForrigeFortsett »
Then take froin your Scale the Lingth of the Line pq 135, and set it from p to 9, and through the point q draw the Line KC, making it to contain in Length 216 : Nexa take froin your Scale 112, and set it from q to R, and through the point R draw the Line KD, and take from your Scale 217, and set it from K to D, and so proceed till you have finished your Plot. i And, Lastly, Through the several points A B CD, &c. draw the Boundary Lines.
Hum to take the Plot of a Field by the plain
Tuble, at one or more Stations. There are three ways for doing this work. The first performs the Work by ineasuring every Line from the Instrugjent to the Angles, and is a good way, when it can be done. The second does it, by Mealur. ing only the Stations or Distances, and is very quick, but not lo sure and exact as the others yet if it be manag'd by a fkilfull Arrit, it will come near enough the matter in many cases; as Measuring for Mowing or Reaping Fields by the Acre, or in Case of Law Suits, when you cannot come nigh the Ground to be Measured.
The 3d is by way of Circulation, the Instrument being oft to be planted, and the plot to be ineasured by going round about it, by which thick Woods or Bogs may be measured.
In all these Methods two things are to be performed.
1. At every Angle where there is no Mark already, as a Tree, or Bus, &c. one must be placed with a white Paper; or one must go from Angle to Angle.
2. When ever you have occasion to plant your Instrument more then once, you must be sure to let it ftand just as it did the first time, that is, for Situation, which if your Needle be good, will perform the Work , but is not inought sufficient without a backfight and fore-fight. Now for the firft Method.
To take the Plot of a Field at oue Station, in
any part thereof, from whence you may see all its Angles or Corners,
Fig. 92. Suppose ABCDEF be a Field to be measured. First, Cause marks to be set up in every Corner of it ; then make Choice of some convenient place therein, from wher.ce you may best view all the Angles thereof; in which place at H, plant your Table (covered with a Sheet of clean Paper,) Iurn the Table about till che Needle" stand over the Flower de Luce, and fo faften it with the Screw.pin, that the Tible ftir not. Then placing your Index upon the Table, lay the Fiducial Edge thereof upon the point H, representing the
place of your S:ation; and draw a Line with your Compasses point, by the side of the Index upon the Paper ; which done, die rect your fight to B, (Aill keeping the Edge of your Index to the point H) and draw a Line as before, and so in like manner direct your Index to C, D, E and F, drawir g the Lines upon the Paper by the Edge of your Index, with the point of your Compasses, and so having finished the same, measure withyour Chain the distance of every of those Marks, from the place of your Station at H, and then by the help of your Scale and Compasses, sec the same distances from the point H, in the Lines drawn upon the Table, inaking a fmall prick with your Compasses point at the end of every one of them then with the point of your Black-lead Pencil, draw a linall Line from one point to another, as nainely from A to B, from B to C, from C to D, &c. fo shall you have upon your Table the exact Plot of your Field.
To take the Plot of any Field at one Station,
in any one Angle thereof, from whence all o; iher Angles may be seen.
Fig.93 Firft,as before set upMarks in every Corner of the Field, as at BCDEFG ; tben make Choice of the most convenient Angle therein ; from whence you may beft view all the reft, as A; and having fixt your Table
there, as before is taught, apply the Index to the point A, and direct the sights to B; then draw a Line AB upon the Paper, and with your Chain measure the Length there. of, and set it down by the help of your Scale from A to B.
Then from the said point A, turn your sghts to C, your second Mark, and then draw with one point of your Compasses upon the Paper the Line AC, measuring the distance, and feting down the Lergh as you were before taught.
In like manner direct your fights to D, E, Fand G, and drawing Lines upon your Paper, measure with your Chain the Diftance of each of the same Angles, from your Station point at' A, where your Table is planted; then with your Compasses take from the Scale the respective distances, and and let them down from the point upon the several Lines, and fo del ribe the Lines AB, BC, CD, DE, EF, FG, GA; which will exactly represent the just Fgure of
How to take the plot of a Field at two Stations,
when all the Angles cannot be seen at one.
It oftentimes happeneth, through Hills or the largeness of Grounds, that you can not from any one place of th• Field see all the Corners thereof; in which Cale you must
make Choice of two convenient places within the same : Sɔ that here you are to perform at two Stations, what you did be. tore at one,
Fig, 94. Sippose therefore, that the Figure CDEFGHÍKLM, be a Field to be plotted ; I inake Choice of two Stations, within the same, as A and B, where I can view all the Angles. And first, I plant my Table at A, from whence I can see the Angleş M CDEF; then placing the Edge of my In. dex upon the point A, I direct my fights severally to the Angles within my View, as to MCDEF, drawing Lines, as is directed in the F gure ; which done, I incafure
I every one of them with my Chain, and note them down from iny Scale, as formerly.
Then (my Table remaining fixt) I view the other parts of the Field, and make choice of the point B for my second Station, because from thence, I can see all the other Ai gles of the Field; then setting up a Márk theie, I go back to my first Station at A, (where my Table stands fixed, as I left it,) upon which poin! I mave my Index, till througla t'ie fights thereof, I efpy the Mark at B, which done, I draw a Lineby the Edge of the Index, with the point of my compafs,extending is the Length of my Table, as is represented by the Line ZX; which bring thus performed, I measure my Stationary distance