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the meridian of any place, it will be of perpetual use for observations in the northern hemisphere, and any noted stars, when on or near the meridian, may be observed with it, it not being material whether the stars you observe by be directly on the meridian or not, provided they are near it; all that is required being such a position as can be determined with certainty.  The two pointers in the [[underline]]Great Bear[[/underline]] will be of excellent use; they being on the meridian near the same time: in short al the constellations above the pole afford proper stars of the second magnitude, vis. [[underline]]Auriga, Perseus, Cassiopoeia, Cepheus, Little and Great[[/underline]] Bear, &c. so that all times of the year you will have stars for your purpose, either above or below the pole, as suit best with your latitude: for note, that if your latitude be less than 35 degrees, stars on the meridian, above the pole, may be best observed; but if more than 35 degrees, then those below the pole are best.  In the same manner may observations be made in the southern hemisphere.  There are two stars in the [[underline]]Crosiers,[[/underline]] whose right ascension is the same, according to D.r [[underline]]Edmund Halley[[/underline]]'s observations: There are likewise other constellations about the south pole that I am not acquainted with, which, no doubt, will do as well as those in the northern hemisphere, and be worth the notice of those who sail in those parts.
    Now to illustrate this by an example; suppose a ship at [[underline]]Liverpool[[/underline]] ready for departure, on the 1.st of [[underline]]April[[/underline]], for the continent of [[underline]]America[[/underline]]; as, at this time, the first star in [[underline]]Orion's[[/underline]] belt cannot be seen, one must therefore be taken near the pole, which, as the pole is [[caret]]here[[/caret]] elevated a little above 53 degrees, will suit best on the meridian under it, and may be found in [[underline]]Cassiopoeia[[/underline]]'s side at eleven o'clock at night.  Being provided with your sandglass, regulated as above directed, observe carefully by your thread and plummet when the star comes on the meridian, or rather right under the polar star; the moment the thread cuts both stars, cause your glass to be turned, and proceed on your voyage; you will then have these three particulars always given, vis. your sand-glass being always regularly turned the moment it is out, will shew the time when those stars come on the meridian of [[underline]]Liverpool[[/underline]], or place departed from; your thread and plummet will shew when they come on the meridian of the place the ship is in; and a good watch, or spring clock, will shew the time between, with sufficient exactness in hours and minutes, which is the angle at the pole, ever equal to the difference of longitude.
    Now after twenty days sailing, we will suppose that the aforesaid stars come on the meridian of [[underline]]Liverpool[[/underline]], or place departed from, two hours and 45 minutes before they come on the meridian of the place the ship is in; or, which is the same thing, that your glass is turned two hours 45 minutes