THE ANTI-TEADES OR PASSAGE WINDS. 195 



however, to be more Northerly, as if the Easterly wind interfered with their 

 usual progress to the North-Eastward. 



Considering the normal state of the wind, it seems clear that in so far 

 as the direction of the wind is concerned, a sailing ship bound from England 

 to America at this season of the year (February), should keep her yards 

 well in, and gain good way, even though she may get driven to the North- 

 ward by the South- Westerly winds which prevail on the Eastern side of 

 the Atlantic, for there is good reason to expect that the wind will draw to 

 the Northward of West as she gets over to the Westward. The chances 

 of meeting with ice, and other risks, would of course need careful con- 

 sideration. 



The very little progress (360 miles in a direct line N. ^ E. from lat. 

 31° 30' N., long. 72° 30' W., to lat. 38° N., long. 71° 15' W.),made during 

 the 11 days by No. 38 (the sailing ship Nicoline), bound from Santos to 

 New York, makes it probable that she would have gained by making her 

 northing several degrees farther to the Eastward, where the charts show 

 that a Southerly wind prevailed ; instead of closing with the land, where 

 there was an almost constant fresh Northerly wind. 



This paper gives sufficient evidence of the caution needed when a S.E. 

 wind sets in with a falling barometer. Captains used to the trade know 

 these gales well.* 



It is not necessary to repeat here what has already been said in the 

 Barometer Manual, on the use of the barometer to seamen, and its various 

 action depending on a ship's course and speed. 



Mr. Meldrum, the meteorologist of the Mauritius, in pursuing a similar 

 enquiry with regard to the weather in the Southern Indian Ocean, finds 

 that there waves of high and low pressure follow each other on an Easterly 

 course at an average speed of about 20 miles per hour. 



It will be remembered that we find these waves to travel at the rate of 

 30 or 40 miles per hour. When we consider how the Northern part of 

 the North Atlantic is much more surrounded by land than the Southern 

 part of the Indian Ocean, causing more sudden differences of temperature, 

 we may well suppose that the differences of pressure will be greater in the 

 North Atlantic, giving more activity to the changes of weather. 



Mr. Meldrum also finds that the Hurricanes of the Southern Indian 

 Ocean take their origin in the district lying between the N.W. Monsoon 

 and S.E. Trade, where the barometer is generally lower than to the North- 

 ward and Southward, just as we have already stated that the winter gales 



* In connection with barometric changes, we may here advert to the constitution of 

 the atmosphere, as mentioned (12) on page 102. To that statement we add the follow- 

 ing conelusions arrived at by Professor Dove, of Berlin, from his observations. 



In the l^orthern Hemisphere, the Barometej- falls during E.S.E. and East winds ; 

 passes from falling to rising during S.W. winds ; rises with those from W.N.W. and 

 North ; and has its maximum rise with a N.E. wind. 



The Thermometer rises with E.S.E. and South winds ; has its maximum with S.W. ; 

 falls with W.N.W. and North; and has i!;S minimum with N.E. winds. 



The Elasticity of Vapour increases Vi^ith E.S.E. and South winds ; has its maximum at 

 S.W.; and dimiaishes during the wind's progress by West and N.W. to North ; at N.E. 

 U has its minimum. 



