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 are on the line the pole star stands 3 deg. 30 min. below the pole: if they are on the eastern arm the pole star is one degree below the pole. When one wishes to take the altitude of the pole star, in whichever of the above-mentioned four places the Guard stars may be, the degrees which the pole star has above the pole will be subtracted from its altitude, or those which it has below the pole will be added to it. I have spoken in the account of the voyage of the stars of the Antarctic Pole.

"The latitude of the place may also be ascertained by the sun's altitude. 1. If you find yourself between the equinoctial and the arctic pole and the shadow falls towards that pole, look how many degrees and minutes meridianal declination the sun has that day; and this you will subtract from the altitude of the sun which you have taken: afterwards, deducting the remaining degrees from 90 deg., you will have in the residue the number of degrees of North latitude, that is your distance from the equator. 2. If the sun has a boreal declination, in such a manner that the shadow falls towards the south, take the sun's declination on that day, and add it to the sun's altitude which you have taken, from that sum subtract 90 degs., and the remaining degrees will indicate your boreal latitude. 3. If the sun is between the equinoctial and the antarctic, and the shadow falls towards the antarctic, observe the sun's declination for that day, subtract it from the altitude taken, according to the first rule, and you will have the degrees of south latitude. 4. If, when you and the sun are between the equinoctial and the antarctic pole, the shadow falls