MODE OF DETERMINING A MERIDIAN LINE.
Take a small piece of board, perfectly level, and place in the middle a needle C, three inches high, so that it shall be exactly perpendicular. Expose it to the sun before noon, at 8 or 9 o'clock, and mark the point B at the end of the shadow cast by the needle. Then opening the compasses, with one point on C and the other on the shadow B, describe an arc AB. Leave the whole in this position until afternoon when you see the shadow just reaching the arc at A. Then divide equally the arc AB, and taking a rule, and placing it on the points C and D, draw a line running the whole length of the board, which is not to be moved until the observation is completed. This line will be the meridian of the place you are in.
And in order to ascertain the declination of the place where you are with reference to the meridian, place a compass, which must be rectangular, along the meridian line, as shown in the figure above, there being upon the card a circle divided into 360 degrees. Divide the circle by two diametrical lines; one representing the north and south, as indicated by EF, the other the east and west, as indicated by GH. Then observe the magnetic needle turning on its pivot upon the card, and you will see how much it deviates from the fixed meridian line upon the card, and how many degrees it varies to the northeast of northwest.