B. TERRESTRIAL PHYSICS AND METEOROLOGY. 109 



one tenth of a decree to the fathom. In summer the surface 

 strata are thus highly superheated, while their cooling in 

 winter is very feeble. These relations correspond exactly 

 with the tendency of the water to arrange itself in strata of 

 equilibrium, with the least dense layers at the surface. 



The general conclusions at which Professor JVIohn arrives 

 may be summed up as follows : first, that the surface of the 

 sea in currents in narrow sounds in summer is colder than in 

 neighboring places where there is a wider sheet of water ; 

 second, that an effect of the reverse kind takes place in winter, 

 but to a much feebler degree ; third, that both effects to- 

 gether diminish the yearly range of the temperature of the 

 surface of the sea; fourth, that these circumstances influence 

 in the same direction the temperature of the air over such seas 

 and sounds, and that hereby a part of the anomalous strongly 

 marked oceanic character which places in such situations ex- 

 hibit is accounted for. Jour. Scottish Meteorol. Soc, October, 

 1873,73. 



THE TIDES OF TAHITI. 



In 1856 the United States Coast Survey obtained a series 

 of observations of the tides of Tahiti, which showed a re- 

 markable peculiarity; namely, that the solar tide is for the 

 most part greater than the lunar tide. Professor Ferrel, in 

 discussing these tides, has shown that this peculiarity is not 

 the result of any exception to the general theory of tides, as 

 has sometimes been supposed ; but that certain constants in 

 the tidal expressions, which have to be determined by obser- 

 vations, are unusual in this case. There is one other instance 

 of the kind known. It is impossible as yet to specify what 

 are the irregularities in the bottom of the ocean and in the 

 adjacent coast Which occasion the phenomena; but that they 

 are due to such irregularities seems unquestionable. New 

 York Daily Tribune, April 25, 1874. 



THE DEPTH OF THE PACIFIC OCEAN. 



Pecent soundings in the eastern part of the Pacific Ocean 

 indicate that its bed is singularly level. The United States 

 steamer Tuscarora, having finished its first cruise between Cape 

 Flattery and Unalashka, as well as between Cape Flattery 

 and San Francisco, lias recently completed a survey from San 



