VOL. I.] PHILOSOPHICAL TRANSACTIONS. 51 



professor of geometry in Gresham College, to draw up heads of enquiries for 

 the use of seamen in making obser\'ations. in their voyages, which he accord* 

 ingly executed, as below : — 



1 . To observe the declination of the compass, or its variation from the me- 

 ridian ; noting also the latitude and longitude of the place where such obser- 

 vation is made, and stating the method of taking them. 



2. To carry dipping needles with them, and observe their inclination. 



3. To observe carefully the tides in as many places as they can, with all the 

 circumstances ; such as the precise time of ebbing and flowing in rivers, and at 

 capes ; the set of their currents, the perpendicular distance between the highest 

 tide and lowest ebb, in spring and neap tides ; what day of the moon's age, and 

 what times of the year, the highest and lowest tides happen. 



4. To make plots and draughts of coasts, promontories, islands and ports, 

 marking the bearings and distances as near as may be. 



5. To sound and mark the depths of coasts, ports, and other places near the 

 shore*. 



6. To observe, in all soundings, the nature of the ground at the bottom of 

 the sea, whether it be clay, sand, rock, &c. 



7. To keep a register of all changes of the wind and weather at all hours, 

 both day and night, the point the wind blows from, and whether strong or 

 weak ; the rains, hail, snow, &c., the precise times of their beginnings and 

 continuance, especially hurricanes and spouts ; and above all, carefully to ob- 

 serve the trade-winds, about what degrees of latitude and longitude they first 

 begin, where and when they cease, or change, or grow stronger or weaker, and 

 how much. 



8. To observe all extraordinary meteors, lightnings, thunders, ignes fatui, 

 comets, &c., marking the places and times of their appearing, continuance, &c. 



g. To carry with them good scales, and glass-vials of about a pint, with nar- 

 row mouths, to be filled with sea-water in different latitudes, in order to know 

 its weight, both of the water near the surface and at greater depths. 



Of the Shadow of one of Jupiter s Satellites, seen by a Telescope, 

 passing over the Body of Jupiter. N" 8, p. 143. 



On the 26th of September last, at half an hour after seven o'clock, was seen, 

 both in Holland and in France, the shadow of one of the satellites of Jupiter, 



lectures withdrew into his apartments to converse together : These meetings at length gave rise to the 

 Royal Society itself; of which great and usefiil institution Mr. Rooke was a zealous promoter ; 

 though he did not live till it received its establishment by the royal charter, as he died the 2J th of 

 June, 1662, in the 40th year of his age, universally respected and regretted. 



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