LET.IX. OF THE LATITUDE AND LONGITUDE.

places under consideration; for these being onceknown, by only turning to a common map orglobe, the places themselves will be found byinspection. What is to be understood by theseterms, and how they are applicable to the pur-poses mentioned, you will, no doubt, be anxiousto enquire; and I stiall endeavour to satisfy yourcuriosity to the utmost of my power. The sub-ject is no less useful than curious, being thevery foundation both of geography and naviga-tion ; and, in order that you may obtain as clearan idea of it as possible, we will begin with thefirst principles, and proceed gradually, step bystep, to their application.

In the first place, then, as it is absolutely ne-cessary for you to have a perfect conception ofwhat is meant by the poles of the earth, theequator, and the meridians, I shall describe themin as familiar a manner as the subject will admit,and at the same time shew you their use anddesign. The poles are the two extremities ofthe earth’s axis; or those points where the ima-ginary line, round which it performs its dailyrevolutions, meets the earth’s surface: thatwhich is directed towards the most northernpoint of the heavens, being called the northpole; and that which is directed towards themost southern point, the south pole. So thatthey are diametrically opposite to each ether,and always preserve the same relative situation.

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