defcend into it, could vent themselves without fome visible way of being conveyed to the Sea, and the River Nile not be affected with it; but feeing the vast confluence of Water, proceeding from those exceffive Rains, has no other vent but by the Nile, it will neceffarily follow, that the Nile muft overflow it's bounds at thofe rainy Seafons, and yet it's Inundation has no dependance upon the Moon, nor upon the natural Caufes, above affigned, for the regular flowing and ebbing of the Sea.

VOL. II.

X

CHAP.

CHAP. XXXVIII.

Of the Bearing of Places, or the Points they lie in, from one another

PROPOSITION I.

To know in each Place the four Cardinal Points, and the intermediate ones.

TH

HIS is the most neceffary Problem in the whole Art of Navigation, for without it there is no directing a Ship; and the want of this very thing hindered the Antients from failing far. And herein is the chief Difference between the antient and modern failing; for the Antients had no certain Method to find the North and South Points at any time; and therefore durft not trust themfelves into the wide Ocean; but only coafted along the Shores, that they might by fome Signs know where they were.

THE Antients had two ways which are serviceable to the Moderns, for finding the North and South (or a meridian Line) from which the other Points are easily known; 1. By the Stars at Night, particularly the Little Bear, and the Star in it's Tail, called the Pole-Star; which was much famed with Antiquity, and ferved to fhow them the North, and thereby all the other Points; for turning their Face to it, the Eaft was on the right, and the Weft on the left, and the South behind; and they had a Circle with the Points on it, and bringing

the North and South Point, to the meridian Line, the other Points were feen at once.

BUT by Day they ufed the Sun rifing or fetting, as we fhewed in Chap. xxviii.

2. ANOTHER Method they had was by knowing the Situation of the Shores, and of one Promontory from another; for when one Point was thus known, either from the Maps, or by Obfervation and Experience, they could in failing find the reft; but then they could not go far from the Shores, which directed them as to the Points: for they could not at all times ufe the Sun and Stars for that end.

3. A third Method they used, was by obferving the Points they had run in; for knowing how they first directed the Ship, and how much they turned again, their Course from that Point, they knew the other Points.

FROM whence the Reafon appears of their imperfect and dangerous failing; viz. their not knowing the Points in the wide Ocean, fo as to tell how to steer.

THIS third Method by obferving the Ship's Courfe, is of no ufe when the Ship is turned to a great many Points by the raging Sea and Waves.

SO far of their Method of finding the Meridian Line, which was fo imperfect, that they durft never truft themselves in the vaft Ocean, and fo never knew America.

WE have now a plain and eafy Method of finding the North and South Points, and all the rest from them, by the help of that wonderful Property which the Load-ftone, and all Needles of Iron touched with it's Poles, or lying long near it, or even lying long in the Meridian Line, are found to have; which is, that they turn to the North and South, if not hindered; the Load-ftone

X 2

having

SECT. VI. having two oppofite Poles, of which the one turns always to the North, the other to the South, and the other Parts to the other Points; but the North and South Pole of it is only confidered: and the fame Property it communicates to a Rod of maffy Iron, or a fmall Needle, but in a contrary way; for the end of the Needle drawn on the North Pole of the Load-ftone, turns to the South; and that end which is applied or rubbed on the South Pole of the Load-ftone, turns to the North, and is called the North Pole of the Needle: which wonderful Property of the Load-ftone was unknown to the Antients, though, which is ftrange, they were acquainted with it's other Property of drawing Iron to it.

THUS the North and South Points may be eafily found by hanging the Load-ftone, which is carried to Sea with them, by a Thread, that it may turn itself eafily to the North and South; but 'tis better done by applying a Needle to the North Pole of the Load-ftone: for recovering it's Virtue, and drilling a Cap in it's middle, and laying it on the Top of a fharp brass Pin, fo that it may move freely, it will, when it refts, fhow the North and South.

PROPOSITION II.

To make the Sea Compass.

DIVIDE a Circle drawn on a Chart into thirty two Points, and chufe one of them for the North, mark it with the Flower-de-Luce, and count the other Points from it, which are to be marked on it.

THEN let the magnetic Needle be fixed under the Circle drawn on the Chart, fo as the middle of the Needle may be under the Center, and the North Pole on the Chart may be fixed to the North

End of the Needle; then placing the Needle and Chart, fixed to it above, on the brafs Pin, that it may move freely, it will turn about, 'till the Needle lie in, or near, the Meridian Line. By the help of this Compass they can go thro' the vaft Ocean to the moft remote Parts, being guided by the Direction of the Needle. We faid near the Meridian Line, for it doth not point exactly to it; for which fee Prop. vi, following.

PROPOSITION III.

Infinite Points

may be drawn on the Compass; Seamen count fixteen in Small Voyages, and thirty two in greater, but fixty four in the greatest.

OF this we have spoke in Chap. xx. whence may be had an accurate Explication. The Portuguese call the Points Rhombs.

PROPOSITION IV.

The magnetic Needle (as alfo the Poles of the LoadStone itself) points direct North only in a few Places, but in moft Places declines a little to the East or Weft, and that unequally; and so doth not point due North and South.

FOR at one of the Ifles of the Azores, or Flandrian Ifles, called el Corvo, there is no Declination from the Meridian, and the Needle lies exactly in it; and 'tis fo in fome others, tho' not all Parts of that Meridian. In Places fituated eastward from this Ifland to the Promontory of Africa, called Cabo das Agulhas (not far from the Cape of GoodHope) the Needle declines eaftward unequally; fo that to the Ifles of Tristan de Cunha, and feventy Degrees further, the Declination increases fo as to