68 



THE PHYSICAL GEOGRAPHY OF THE SEA. 



toms at Philadelphia alone amounted to $2,941,000,* or more than 

 one half of those collected in all the states together. 



108. Nor did the effect of the doctor's discovery end here. Be- 

 fore it was made, the Gulf Stream was altogether insidious in its 

 effects. By it, vessels were often drifted many miles out of their 

 course witliout knowing it ; and in had and cloudy weather, when 

 many days would intervene from one observation to another, the 

 set of the current, though really felt for but a few hours during the 

 interval, could only be proportioned out equally among the whole 

 number of days. Therefore navigators could have only very vague 

 ideas either as to the strength or the actual limits of the Gulf 

 Stream, until they were marked out to the Nantucket fishermen 

 by the whales, or made known by Captain Folger to Dr. Franklin. 

 The discovery, therefore, of its high temperature assured the nav- 

 igator of the presence of a current of surprising velocity, and which, 

 now turned to certain account, would hasten, as it had retarded 

 his voyage in a wonderful degree. 



109. Such, at the present day, is the degree of perfection to 

 which nautical tables and instruments have been brought, that 

 the navigator may now detect, and with great certainty, every 

 current that thwarts his way. He makes great use of them. 

 Colonel Sabine, in his passage, a few years ago, from Sierra Le- 

 one to New York, was drifted one thousand six hundred miles of 

 his way by the force of currents alone ; and, since the application 

 of the thermometer to the Gulf Stream, the average passage from 

 England has been reduced from upward of eight weeks to a little 

 more than four. 



110. Some political economists of America have ascribed the 

 great decline of Southern commerce which followed the adoption of 



* Value of Exports in Dollars. ^ 



1 Doc. No. 330, H. R., 2d Session, 25th Congress. Some of its statements do not agree with those 

 taken from M'Pherson and previously quoted. 



