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 of Her, as may hereafter serve to build a Solid and Useful Philosophy upon; They have from time to time given order to several of their Members to draw up both Inquiries of things Observable in forrain Countries, and Directions for the Particulars, they desire chiefly to be informed about. And considering with themselves, how much they may increase their Philosophical stock by the advantage, which England injoyes of making Voyages into all parts of the World, they formerly appointed that Eminent Mathematician and Philosopher Master Rooke, one of their Fellowes, and Geometry Professor of Gresham Colledge (now deceased to the great detriment of the Common-wealth of Learning) to think upon and set down some Directions for seamen going into the East & West-Indies, the better to capacitate them for making such observations abroad, as may be pertinent and suitable for their purpose; of which the said Sea-men should be desired to keep an exact Diary, delivering at their return a fair Copy thereof to the Lord High Admiral of England, his Royal Highness the Duke of York, and another to Trinity-house to be perused by the R. Society. Which Catalogue of Directions having been drawn up accordingly by the said Mr. Rook, and by him presented to those, who appointed him to expedite such an one, it was thought not to be unseasonable as this time to make it publique, the more conveniently to furnish Navigators with Copies thereof. They are such, as follow;

1.To observe the Declination of the Compass, or its Variation from the Meridian of the place, frequently; marking withal, the Latitude and Longitude of the place, wherever such Observation is made, as exactly as may be, and setting down the Method, by which they made them.

2.To carry Dipping Needles with them, and observe the Inclination of the Needle in like manner.

3.To remark carefully the Ebbings and Flowings of the Sea, in as many places as they can, together with all the Rh