THE FISHERIES OF THE ADRIATIC, 



hitherto received no satisfactory explanation ; these waves are called 

 Ligazzi. 



, The mean temperature of the air is between 59 and 73 F., that of the 

 water being between 66° and 71 F., and it has been found that, as a rule, the 

 temperature of the water decreases from the coast-line outwards, as also from 

 the surface downwards, this decrease being greater in summer than in winter. 

 This rule is, however, somewhat modified by local influences, such as the 

 influence of the land and the outward atmosphere, as also the prevalence of 

 submarine sources. Thus, it has been ascertained that layers of water, 

 which are in contact with the land, are subject to alterations of temperature 

 altogether independent of this theory, having both a higher temperature in 

 summer, and a lower temperature in winter, than similar layers of water 

 further outwards. 



Again, the surface waters are subject to the influence of the temperature 

 of the atmosphere, hence the changes are more sudden than in lower depths ; 

 thus, in winter, the surface waters may become colder than the deeper layers, 

 and even, as a rule, it will be found that the temperature in winter (February) 

 is almost alike in all depths, the difference being only 1-2 F.; at the same 

 time the temperature does not appear to fall below 45 F. in any zone, even 

 in winter. 



The greatest difference in the various zones is met with in summer, 

 when the surface waters reach 77 F., and exceptionally, when under the 

 direct influence of the sun's rays, or the proximity of the land, even more, 

 whereas the lower zones retain much of their winter freshness. Thus in 

 10 fathoms the temperature never exceeds 72 , in 20 fathoms 66°, and in 30 

 fathoms 6i°. 



The mean temperature of the air in winter is from 40 to 32 F., which is 

 that of the British Isles and both coasts of the British Channel; but the 

 waters retain during winter much of the warmth acquired during the summer 

 heats, and their temperature is higher than that of the air in autumn and 

 winter ; and lower in spring and summer. 



The slower influence of changes of the temperature of the air on the 

 lower zones has the effect that, excepting in summer, warmer layers of water 



