EXPLANATION OF THE PLATES. IxxlK 



I have the confidence, however, to flatter myfelf with 

 the belief, that the new Theory which I have prcfented, rc- 

 fpeding the caufes of the general Currents, and of the Tides 

 of the Ocean, may be rendered ufeful to Navigation. It 

 appears to me, that a vefTel taking her departure hence in 

 the month of March, with thecourfe of our polar effufions, 

 and keeping in the middle of the Atlantic channel, might 

 proceed, in Summer, all the way to theEaft-Indies, conti- 

 nually favoured by the current. This I am able even to 

 prove by the experience of various -Navigators. It is true 

 that, during the feafon which is the Winter of the South 

 Pole, the weathering of the Cape is dangerous, becaufe the 

 wefterly monfoon, which then predominates, in thofe Seas, 

 excites in them frequent ftorms, as well as on the coafts of 

 India, which are oppofed to it ; but I believe thefe incon- 

 veniencies might be avoided, by ftretching out into a higher 

 Latitude. 



The fame veflel might return from the Eaft-Indies, fix 

 months afterwards, during our Winter, aided by the eiFu- 

 fions of the South Pole. Advantage might be taken, on the 

 contrary, of the counter-currents of the general Currents, 

 or of their lateral Tides, to go or return, at the interme- 

 diate feafons, by coafting along the Continents. It is eafy 

 to deduce from this theory other means of information for 

 the navigation of all Seas : for example, affiftance might 

 be derived from thofe currents for the difcovery of new 

 iflands ; for every ifland is fituated at the extremity, or at 

 the confluence of one or more currents, as every volcano is 

 placed in a counter-tide. 



Here I clofe thefe nautical difquifitions, in which there 

 are undoubtedly, inaccuracies of flyle, and manifold im- 



perfedions 



