7G ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



gions, and during the summer a cooling effect; so that the 

 greater the yearly range of atmospheric temperature, the 

 greater the depth in the ocean to which its effect will be felt. 

 lie thus explains the presence of the large body of compara- 

 tively warm water in the North Atlantic, the existence of 

 which has been usually ascribed to an assumed back-water 

 of the Gulf Stream. This warm water is, in fact, due to no 

 such extraneous cause, but is the actual effect of the condi- 

 tions of the climate at the surface, which effects become ap- 

 parent, because the water is free from the influence of oceanic 

 currents, and exposed to the effect of climate alone. Pro- 

 ceedings of the Iloyal Society, 1875, p. 123. 



NAUTICAL METEOROLOGY. 



Nautical meteorology has for its object the study of both 

 atmosphere and ocean in their relations to navigation, and 

 the utilization of our knowledge of the winds and currents, 

 the laws of tempests, etc., in order to accomplish the shortest 

 possible voyages between given points. The foundation of 

 tiiis application of scientific study to the wants of navigation 

 was laid by Maury, and a recent work by Ploix and Caspari 

 seems to embody many of the recent improvements that have 

 been made. This work is intended as a guide to the mariner 

 in the use that he can make of the charts published by me- 

 teorologists. After giving a general descriptive account of 

 interesting phenomena, instruments, methods of observation, 

 and the general climatological features, the volume gives a 

 resume of the oceanic routes recommended for the different 

 months of the year throughout the navigated oceans. For 

 instance, it insists especially upon the importance of attend- 

 ing to the point where the ship crosses the equator in passing 

 from one hemisphere into the other. Thus, in order to go 

 from Europe to either the Cape of Good Hope or to Cape 

 Horn, we should cross the equator at the same point; but, 

 varying with the seasons, we should pass either near the 

 African or near the Brazilian coasts, but never in the inter- 

 mediate region where the navigator is exposed to persistent 

 calms. Another interesting point is the navigation in high 

 southern latitudes, where Ave meet almost constantly west 

 winds. Thus, in order to go to Australia, we sail from Eu- 

 rope to the south of the Cape of Good Hope, but in order to 



