40 THE PHYSICAL GEOGRAPHY OF THE SEA. 



plane of a great circle. The natural tendency of all matter, wlien 

 put in motion, is to go from point to point by the shortest dis- 

 tance, and it requires force to overcome this tendency. Light, 

 heat, and electricity, the howling wind, running water, and all 

 substances, whether ponderable or imponderable, seek, when in 

 motion, to obey this law. Electricity may be turned aside from 

 its course, and so may the cannon ball or running water ; but re- 

 move every obstruction, and leave the current or the shot free to 

 continue on in the direction of the first impulse, or to turn aside 

 of its own volition, so to speak, and straight it will go, and coU' 

 tinue to go — ^if on a plane, in a straight line ; if about a sphere, 

 in the arc of a great circle — thus showing that it has no volition 

 except to obey impulse ; and that impulse comes from the phys- 

 ical requirements upon it to take the shortest way to its point of 

 destination. 



121. The waters of the Gulf Stream, as they escape from the 

 This law recognized ^rulf, arc bouud for the British Islands, to the Korth 

 by the Gulf stream, g^g^^ ^^^ Frozcu Occau (Plate IX,). Accordiugly, 

 they take (§ 118), in obedience to this physical law, the most di- 

 rect course by which nature will permit them to reach their des- 

 tination. And this course, as already remarked, is nearly that 

 of the great circle, and of the supposed cannon ball. 



122. Many philosophers have expressed the opinion — indeed, 

 Shoals of Nantucket thc bclicf (§116) is common among mariners — ^that 

 course. thc coasts of the United States and the Shoals of 

 Nantucket turn the Gulf Stream toward the east ; but if the view 

 I have been endeavoring to make clear be correct, it would ap- 

 pear that the course of the Gulf Stream is fixed and prescribed by 

 exactly the same laws that require the planets to revolve in orbits, 

 the planes of which shall pass through the centre of the sun ; and 

 that, were the ISTantucket Shoals not in existence, the course of 

 the Gulf Stream, in the main, would be exactly as it is and where 

 it is. The Gulf Stream is bound over to the North Sea and Bay 

 of Biscay partly for the reason, perhaps, that the waters there are 

 lighter than those of the Mexican Gulf; and if the Shoals of Nan- 

 tucket were not in existence, it could not pursue a more direct 

 route. The Grand Banks, however, are encroaching (§ 116), and 

 cold currents from the north come down upon it : they may, and 

 probably do, assist now and then to turn it aside. 



