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WHen you would make your Table fit for the field, lay the three boards thereof togeth•• and also the ledges at each end thereof in their due pla•…•… ••ccording as they are mark∣ed. Then lay a sheet of white paper 〈◊〉〈◊〉 over the Table, which must be stretched over all the boards by putting on the Frame, which bindes both the paper to the boards, and the boards one to another.
Then screw the Socket on the back side of the Table, and also the Box and Needle in its due place, the Metidian line of the Card (which is in the Box) lying parallel to the Meridian or Diameter of the Table; which diameter is a right line drawn upon the Table from the beginning of the degrees through the center, and so to the end of the degrees. Then put the Socket upon the head of the Staffe, and there screw it. Also, put the sights into the Index, and lay the Index on the Table, so is your Instrument prepared for use as a Plain Table or Theodolite, the difference only being in placing of the Index, for when you use your Instrument as a Plain Table, you may pitch your center in any part of the Table, which you shall think most convenient for the bringing on of the work which you intend: But if you use your Instrument as a Theodolite, then the Index must be turned about upon the Center of the Table, for which purpose there is a piece of wier which goes through a small hole of brasse fastened to the Index, and so into the center, by which means the Index keepes his constant place, only moving up∣on the center.
Your Instrument being thus ordered, you may use it either as a Plain Table or a Theodolite, but if you would use it as a Circum∣ferentor, you need only screw the Box and Needle to the Index, and both of them to the head of the Staffe, with a brasse screw-pin fitted for that purpose, so that the Staffe being fixed in any place, the Index and fights may turn about at pleasure without moving of the Staffe, and now is your Instrument a good Circumferentor, nay better then that before described in the second Book.
Also, when you have occasion to measure any Altitude, hang the Labell upon the farther Sight, and thus are you exactly fitted for all occasions.