178 OBSERVATIONS ON THE WINDS. 



Mail Steamers' tracks between the Channel and New York.* There were 

 eight of these logs, and for each of them a separate diagram was made 

 (which cannot be given here), exhibiting the character of wind, weather, 

 barometric pressure, air and sea surface temperature, the specific gravity 

 of the sea-water, and the readings of the dry and wet bulb thermometers. 

 Being thus uniformly arranged, a series of important deductions was derived 

 from their teachings by Captain Toynbee, which bear out in a remarkable 

 degree the observations previously made by Sir John Herschel and Mr, 

 Birt, on Barometric Waves (see (36) and (37), pp. 116 — 117 ante). 



(109.) Captain Toynbee remarks : — Having considered the eight dia- 

 grams, I propose giving a few more facts before drawing any conclusions. 

 First, the peculiar undulations in the baromeiric curves, accompanied 

 by corresponding changes in the wind, weather, and temperature, are quite 

 in accordance with the experience of seamen in corresponding Southern 

 latitudes ; there, from the latitude of the Cape of Good Hope down to 

 55° S., a similar series of changes is experienced, the winds commencing 

 at North and ending at West or S.W. ; it will be borne in mind that in 

 this case the South is the polar wind. There, also, ships running to the 

 Eastward seem to keep company with a Westerly gale, so that the wind 

 continues from the same quarter for days. 



With the object of discovering the breadth of these belts of Southerly 

 wind accompanied by a decreasing pressure, and of Westerly wind accom- 

 panied by an increasing pressure, I have calculated the number of geo- 

 graphical miles which the ship steamed to pass through them, and find 

 from seven of those on diagram 1, that each belt occupied about 20 hours, 

 and the ship steamed about 150 miles ; also, that in diagram 1, the 

 Westerly wind belts were about as broad as the Southerly ones. Now, 

 by referring to the homeward passages, it will be seen that the steamer 

 often kept in the same wind for days together, and in some cases had a 

 decreasing pressure with a North- Westerly wind, and an increasing 

 pressure with a Southerly wind ; it therefore seems probable that she then 

 kept pace with the general motion of the gale to the Eastward, and, in 

 fact, sometimes outstripped it, so that we can hardly be wrong in esti- 

 mating that these systems of winds were travelling to the Eastward at 

 least at a rate of about eight miles an hour ; hence, on the outward passage, 

 whilst the ship steamed 150 miles to the Westward, the gale, by a rough 

 estimate, may be said to have moved about 150 miles to the Eastward, 

 giving a breadth of about 300 miles for each of the Westerly and Southerly 

 wind belts. 



(110.) The accompanying quotation from a letter I received from Captain 

 R. Inglis, Marine Superintendent to the Cunard line of steamers, contains 

 the opinion of one who has had great experience in Atlantic weather. He 

 thinks that the Westerly winds of the Atlantic are caused by the meeting 

 of two currents of air ; whether he be right or not, his facts are very in- 

 teresting. Writing from Liverpool, he says : — " Between this country and 

 New York is the route of which I have had most experience, and the 



* " Report on the Meteorology of the Nortn Atlantic, oetween the parallels ot 40° and 

 W N.," by Captain Henry Toynbee, 1369. 



