1871.] 



Theory of the Ocean. 



531 



Atlantic, or of the Black Sea, do not intermingle, and exert their individual 

 temperature in the depths of the central basins. The temperature of the 

 deeper waters of the Mediterranean, Archipelago, Sea of Marmora, and 

 Black Sea are consequently each dependent on local influences, namely 

 from the solar or atmospheric temperature above them. Therefore the 

 minimum temperature of their deeper parts corresponds nearly with the 

 mean annual temperature over them. 



" In the Grecian Archipelago I long since showed it to be constant at 

 about 55° in depths from 100 fathoms downwards. In that sea the 

 temperature of the intermediate depths between 100 fathoms and the 

 surface in the summer season ranges from 55° to 76°, and, indeed, even up 

 to 80° and 86° sometimes, in the littoral waters of enclosed gulfs and 

 shallow bays. 



" In the eastern and western basins of the Mediterranean it will have 

 consequently a higher minimum temperature than that ; and I find that it 

 is about 59° in all depths from 300 down to 2000 fathoms. But between 

 the depths of 30 and of 300 fathoms there is an increasing variation from 

 that temperature to 73° and to 75° in the summer months, but confined 

 more particularly to the depths between 100 fathoms and the surface. 



"But in the winter months of December, January, February, and March, 

 the upper depth is nearly- at the minimum temperature of the deepest part 

 below, namely from 59° to 62°, varying with the locality and depths of 

 water there. 



"Thus it is that in these months the surface and deep waters of the 

 Mediterranean are at a constant temperature of about 10° or 15° above 

 that of the atmosphere. 



"After the month of March, however, the solar influence begins sensibly 

 to raise both sea and atmospheric temperatures, so that in July, in the 

 southern part of the Mediterranean, it is at its maximum of about 75° 

 from the surface down to the depth of about 30 fathoms." 



Having been thus brief in stating the facts obtained in regard to the 

 distribution of the temperatures of the deeps, I shall also be as brief as will 

 be consistent with the due illustration of the more important facts and results 

 in describing the observations for ascertaining these surface- and under- 

 currents in one or two of the localities in question, viz. the Dardanelles 

 and Bosphorus, where Dr. Carpenter has assumed and predicted conditions 

 as an absolute necessity, and upon which predictions he has mainly founded 

 his enlarged views and theories. 



Now it will easily be realized on consideration, that the testing of 

 surface-currents for their various rates in different depths, or of under- 

 currents of small amount where they exist, in proof of this theory, as a 

 general fact, is an experiment that requires much delicacy and nicety in 

 the mode of operation and the means by which it is attempted or effected. 

 I therefore never attempted such experiments by the use of any bulky 

 object, such as a boat, that offered both great resistance to the surface* 



2 t 2 



