56 



H\ DROGR APHY. 



[Sect. III. 



Sect. 



] 



S 



s 



tudes, the commencement or termination of the monsoon, 

 of any positive change of current, or from any continued 

 state of things to another, the whole effect of the current 

 for the period should be deduced, and an average of it 

 daily rate and set be given, together with any remark 

 which may be considered useful. 



3. With the direction of the current thus determined, 

 it is very desirable to connect the temperature of the sur- 

 face of the sea, for it has been by such observations that 

 we have been able to trace, with a certainty amounting 

 almost to proof, the continuous course of the same body 

 of water for thousands of miles over the troubled surface 

 of the ocean, and that other curious and important facts in 

 physical hydrography have been ascertained. We would 

 therefore urge attention to the subject as one of con- 

 siderable importance to navigation. As a proof of its 

 influence upon a passage, we need only 

 remarkable phenomenon of the Equatorial and Guinea 

 currents : two streams in contact, but flowing in opposite 

 directions, and having a temperature differing 10 or 12 

 degrees from each other, and yet pursuing their opposite 

 courses for upwards of a thousand miles ; and according 

 as a vessel is placed in one or the other of these currents, 

 will her progress be aided or retarded from 40 to 50 

 miles a day.* 



instance the 



Cou 



J. 



t/^ -^ Vi'*--^ *hj ^/ %^ J.AM, mj \^JL «.fVV Vt* ^-' *^ * 



the surface of the sea jfrom every ship in active service, 



we should be able in a short time to construct tables 

 showing the normal temperature of the surface of the 



every 5° of latitude for every month in the 



* Sauiiic's * Hydrographical Notices.' 



ocean lor 





1 





> 



year 



parti' 

 differ 

 canst 

 oiarli 

 teat 



tardii 

 and i 

 lead 

 chan^ 

 where 

 over i 



It 



curr.. 

 and i 



houi 



x/^ 



in the 



mad 



e 



lie'- ' ( 

 4. ■ 



tile oc 



appea 

 floati 



V\ 



oflers 



"It 



> 



Mf 



Moving 

 * Co 



