APPENDIX, 



XV11 



In the Mexican Gulph which abounds with banks and shoals, my brother thought 

 he met with confirmation of Dr. Davy's assertion that the water of the sea gets sensi- 

 bly cooler in the vicinity of a sand or shelving shore ; I confess however on looking 

 over his Tables the fact seems still dubious, resting generally on an equivocal semi- 

 degree. Dr. Russell and myself could not perceive any influence on approaching the 

 Sandheads, but that may have been prevented perhaps by the strong current from the 

 Hooghly in the month of September. 



6. My brother at first asserted, contrary to Dr. Davy that the surface of the sea 

 experienced no change of heat in the night : he has since found however that in very 

 smooth water there is a difference amounting to about one degree between the ex- 

 tremes, which are nearly at sunset and sunrise. Davy calls it 2°. 



• 7. It might be imagined that the three great oceans of the world would present 

 an average of equal temperatures nearly, at equal distances from the equator, but 

 this is far from being the case. The Atlantic is colder than the Indian Ocean, and 

 this (according to Kotzebue) colder than the Pacific. The West South Atlantic ex- 

 ceeds the East in heat by several degrees. Probably all these discrepancies might be 

 explained by due attention to their prevalent winds and currents, or if not, the cause 

 may lay in the different depth of their beds of which we can acquire no certain know- 

 ledge. I will conclude by presenting the mean results of three voyages calculated by 

 my brother. 



Mean Temperature of the Ocean in \ 



'he Tra 



ck of George Pi 



insep, Esq. 





North Atlantic. H South Atlantic. 



South Indian. 



North Indian. 



Equator, to 1 9° Lat. 

 Ditto, 23 

 Diuo, 37 



77.8 

 76.5 

 75.1 





80.6 

 80 2 

 73.4 



6 5 « 



-5^0 



,3.3 



76.36 



76 17 



1 72.9 



>VI» 



- •-* 



81°.7 



VI 



3 



*** 



Mean Temperatures in the Track of James Prinsep, Esq. 



Equator to 19° Lat. 

 Diuo, 23 



Ditto, 37 



North Atlantic I South Atlantic 



77.46 



76.5 



73.7 



76.68 



76.0 



71.0 



South Indian. 





— f . 



78.36 



S*s* 



77.0 



if..- o" 



71.5 



3 M-O 





J 



North Indian. 



81.75 



E 



