68 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



among them — inform us that it was no uncommon occurrence for 

 vessels bound for the Capes of the Delaware in winter to be blown off 

 and to go to the West Indies, and there wait for the return of spring 

 before they would attempt another approach to this part of the coast. 



186. Accordingly, Dr. Franklin's discovery with regard to the 

 Thermal navigaiioii. Gulf Stream tcmpcrature was looked upon as one 

 of great importance, not only on accoimt of its affording to the 

 frosted mariner in winter a convenient refuge from the snow-storm, 

 but because of its serving the navigator with an excellent land- 

 mark or beacon for our coast in all weathers. And so viewing it, 

 the doctor, through political considerations, concealed his discovery 

 for a while. The prize of 20,000/., which had been offered, and 

 partly paid, by the British government, to Harrison, the chro- 

 nometer maker, for improving the means of finding longitude at 

 sea, was fresh in the minds of navigators. And here it was 

 thought a solution of the grand problem — for longitude at sea 

 was a grand problem — had been stumbled upon by chance ; for, 

 on approaching the coast, the current of warm water in the Gulf 

 Stream, and of cold water on this side of it, if tried with the ther- 

 mometer, would enable the mariner to judge with great certainty, 

 and in the worst of weather, as to his position. Jonathan Wil- 

 liams afterwards, in speaking of the importance which the thermal 

 use of these warm and . cold currents would prove to navigation, 

 pertinently asked the question, " If these stripes of water had been 

 distinguished by the colours of red, white, and blue, could they be 

 more distinctly discovered than they are by the constant use of the 

 thermometer ?" And he might have added, could they have 

 marked the position of the ship more clearly ? 



187. When his work on Thermometrical Navigation appeared, 

 Commodore Truxton. Commodoro Truxtou wroto to him : " Your pub- 

 lication will be of use to navigation by rendering sea voyages secure 

 far beyond what even you yourself will immediately calculate, for I 

 have proved the utility of the thermometer very often since we 

 sailed together. It will be found a most valuable instrument in 

 the hands of mariners, and particularly as to those who are unac- 

 quainted with astronomical observations ; * * * * these particularly 

 stand in need of a simple method of ascertahiing their approach to 

 or distance from the coast, .especially in the winter season ; for it is 

 then that passages are often prolonged, and ships b'own off the 

 coast by hard westerly winds, and vessels get into the Gulf Strerm 

 without its being known ; on which account they are often hove to 



