274 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



526. It is by trains of reasoning like tliis that we are conti- 

 Excecding interest nually reminded of the interest wliich attaches to 

 research at fei!''^'^^ the observations which the mariner is called on to 

 make. There is no expression uttered by nature wliich is un- 

 worthy of our most attentive consideration — for no physical fact 

 is too bald for study — and marmers, by registering in their logs 

 the kind of lightning, whether sheet, forked, or streaked, and the 

 kind of thunder, whether rolling, muttering, or sharp, may be fiir- 

 nishino* facts which will throw much lio-ht on the featm-es and 

 character of the clouds in different latitudes and seasons. Physical 

 facts are the language of Natm-e, and every expression uttered by 

 her is worthy of our most attentive consideration, for it is the voice 



of AViSDOM. 



CHAPTEE XII. 



§ 531-555. THE GEOLOGICAL AGENCY OF THE WINDS. 



531. Properly to appreciate the various offices which the winds 

 The sea and air re- and tlic wavcs pcrform, we must regard nature as 

 the s!iim machine, a wholc, for all the departments thereof are m- 

 timately connected. If we attempt to study in one of them, we 

 often find om'selves tracing clews which insensibly lead us off mto 

 others, and, before we are aware, we discover ov;rselves exploring 

 the chambers of some other department. The study of drifts takes 

 the geologist out to sea, and reminds him that a knowledge of 

 waves, winds, and currents, of navigation and hydrography, are 

 closely and intimately connected with his speciality. The astro- 

 nomer directs his telescope to the most remote star or to the 

 nearest planet in the sky, and makes an observation upon it. He 

 cannot reduce this observation, nor make any use of it, until he has 

 availed himself of certain principles of optics — until he has con- 

 sulted the thermometer, gauged the atmosphere, and considered 

 the effect of heat in changing its powers of refraction. In order 

 to adjust the pendulum of his clock to the right length, he has to 

 measure the water of the sea and weigh the earth. He, too, must 

 therefore go into the study of the tides ; he must examine the 

 earth's crust, and consider the matter of which it is composed, 

 from pole to pole, circumference to centre ; and in doing this, he 

 finds liimself, in his researches, alongside of the navigator, the 

 geologist, and the meteorologist, with a host of other good fellows, 



