PHILOSOPHICAL 
TRANSACTIONS. 
The Contents. 
DireBiomfor Obfervationsand Bxferiments to he made hj Ma(lers 
of ship 5 Pilots 5 and other fit Perfons in their SeA^JTojages <f 
Printed with Enlargements and Explications of wh^i was formerly 
fublifht of this Kind % ff^ggefted partly by Sir R . M6ray , partly by 
Mr. Rook^ aS) The feveralwayes of obferving\ both at Sea and 
Land\ the Decimations and Variations of the Needle Some 
wajes of knowing the different Gravities of Sea-water : J Form 
of 4 Scheme 3 reprefenting at eneview ^ to the eye ^ obfervations 
of the Weather for a whole Monet h , &c. 
DIRECTIONS 
For Olfervattons and Experiments to be made 
by z5\d afters of ShipSy Tilots^ and other fit 
Perfons in their Sea-Voyages. 
^ Hough the Ait of Navigation , one of the moft ufeful in the 
'i World, be of late vaftly improved, yet remain there ma- 
ny things to be known and done , the knowledge and performance 
Xvhereof, would tend to the accomplitoent of it : Asthe making 
of exa(ft Mapp of all Coafts, Ports, Harbors, Bayes , Promonto- 
ries 5 Iflands 5 with their feveral Profpeds and Be^arings De- 
fcribingof Tydes, Depths, Currents , and other things confider- 
ablein the Seas: Turnings, PafHiges, Creeks^ Sands ^ Shelves^ 
Rocks, and other dangers : Nice Obfeivations of the Variations 
L 1 1 and 
