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and Dippings of the Needle, in different places, and in the same place, at different times: The Winds, Weather, and Tempers of the Seasons every where: The great Depths, Ground, and Vegetables at the bottom of the Sea: The various Degrees of Saltness of the Sea-water, in several places, and at several Depths at the same place. If besides Astronomical things, to be hereafter lookt into, the following Experiments be carefully made, and Directions observed by as many Ingenious Persons, as have opportunity, it may fairly be hoped, that from multitudes of Experiments and Observations, such Rules may be framed, as may be of inestimable use for Seamen. To which purpose the Royal Society, having some years ago, ordered that Eminent Mathematician Master Rooke, one of their Fellows, and Geometry Professor of Gresham Colledge (since deceased, to the great detriment of the Common-wealth of Learning) to draw up some Directions for Seamen, the better to capacitate them for making such Observations abroad, as might be pertinent and suitable to the purposes above-mentioned; such Directions were drawn up accordingly, and soon after printed in Num. 8. of these Transactions. But, further to incourage and facilitate the Work of those, that shall be engaged to put them into practice, it was thought fit, that what of this Kind was heretofore but barely proposed, should now be publisht with ample and particular Explanations, and considerable Additions; which done, a good number of such printed Copies is, by the Care, and at the Expences of the R. Society, to be lodged with the Master of Trinity-house, to be recommended to such, as are bound for far Sea-Voyages, and shall be judged fit for the performance: who are also to be desired, to keep an exact Diary of such observations and Experiments, and deliver 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 said R. Society.
The
