§ 178-181. GULF STREAM, CLIMATES, AND COMMERCE. 63 



perature of the surrounding air, causing it to expand and ascend 

 still higher; and so winds are again called for. Ever ready, they 

 come; thus we have a fourth way. (5.) Innumerable rain-drops 

 now begin to fall, and in their descent, as in a heavy shower, they 

 displace and f)ress the air out below with great force. To this 

 cause Espy ascribes the gusts of wind which are often found to 

 blow outward from the centre, as it were, of sudden and violent 

 thunder-showers. (6.) Probably, and especially in thunder-storms, 

 electricity may assist in creating movements in the atmosphere, 

 and so make claim to be regarded as a wind-producing agent. 

 But the winds are supposed to depend mainly on the power of 

 agents (2), (3), and (4) for their violence. 



178. These agents, singly and together, produce rarefaction. 

 Storms in the inte- diminish prcssurc, and call for an inward rush of 



rior attracted by the . /, . -i • i nr t~\ i 



Gulf Stream. air from either side. Mr. Espy asserts, and quotes 



actual observation to sustain the assertion, that the storms of the 

 United States, even those which arise in the Mississippi Yalley, 

 travel east, and often march out to sea, where they join the Gulf 

 Stream in its course. That those which have their origin at sea, 

 on the other side of the Gulf Stream, do (§ 174) often make right 

 for it, is a fact well known to most observant sailors. Hence the 

 interest that is attached to a proper series of observations on the 

 meteorology of the Gulf Stream. 



179. Sailors dread its storms more than they do the storms in 

 storms of-dreaded ^^^7 othcr part of the ocean. It is not the fury of 

 by seamen. ^j^^ storm alouc that they dread, but it is the "ugly 

 sea" which these storms raise. The current of the stream run- 

 ning in one direction, and -the wind blowing in another, create a 

 sea that is often frightful. 



180. The influence of the Gulf Stream upon commerce and navi- 

 Koutesformeriygov- nation. Formcrlv the Gulf Stream controlled com- 



erned by the Gulf "^ i a i • i • i • 



Stream. mcrcc across the Atlantic by governing vessels m 



their routes through this ocean to a greater extent than it does, 

 now, and simply for the reason that ships are faster, nautical in- 

 struments better, and navigators are more skillful now than for- 

 merly they were. 



181. Up to the close of the last century, the navigator guessed 

 Difficulties irith ear. ^s much as hc Calculated the place of his ship; ves- 

 ly navigators. gg|g ^^^^ Euiopc to Boston frequently made New 



