THE ANTI-TRADES OR PASSAGE WINDS. 181 



water generally exists, after which streaks of warm and cold water were 

 met with. On reaching longitude 65° W., a sudden decrease took place 

 in the temperature of the surface water, with water somewhat warmer 

 farther to the Westward. 



The Specific Gravity is a difficult observation to make on board ship 

 when there is much motion. Captain Martyn and Captain Watson fre 

 quently found the water warmer at 20 feet deep than at the surface, which 

 taken together with the fact that the cold water has the least specific 

 gravity, makes it possible that the Gulf Stream passes under this oold 

 water on its way to the North-Eastward.* 



(113.) The dry and damp bulbs show clearly that the West and N.W 

 winds were generally the driest experienced during the eight passages, but 

 there happened to have been very little Easterly wind. There are some 

 striking instances of extreme dryness in air which, having passed over 

 cold, was then over warm water. 



2. Storms in the Nobth Atlantic Ocean, Between Lat. i.Q° & 55°. 



(114.) A careful study of any series of the North Atlantic Weather 

 Charts will show that Northward of the Trades the general tendency of 

 atmospheric disturbances is from West to East, or from W.S.W. to E.N.E. 

 Nevertheless, there is no certainty that any Storm met with will follow 

 the usual path ; it may suddenly turn off in a different direction, or may 

 disappear altogether. They also vary greatly in their area ; one may cover 

 the whole extent of the Northern Atlantic Ocean, while another may be 

 of very limited dimensions. Many vessels widely apart may be involved 

 in the same disturbance, or two vessels, comparatively close together, may 

 meet with totally different weather. One may be experiencing a violent 

 gale, of which the other may be in complete ignorance. This variation, 

 in the shape and size of a Storm system, is one of the most harassing 

 uncertainties with which the navigator has to deal. He knows by careful 

 watching of his barometer that there is bad weather in his immediate 

 vicinity, he ultimately decides his position with regard to the approaching 

 disturbance, but the magnitude, limits, and intensity he can know nothing 

 of until he has experienced its extent and felt its violence. 



Several storm areas travelling to the Eastward sometimes follow one 

 another in quick succession, moving along their path at an average speed 

 of 18 to 20 miles an hour. In this case, vessels bound in opposite direc- 

 tions would apparently meet with different weather at the same time in 



• In Captain Watson's last log I find the following entry: — IMarch 27th, 18G9, position 

 at noon, lat. 40' 42' N., long. 63° 28' W. 



Noon, surface temperature 67° ; specific gravity 1-0270 

 2 p.m. „ 38°; „ 10260 



4 p.m. „ 88°; „ 



5 p.m. „ 52°; „ 1-0265 

 (The ship was steaming to the Eastward). 



Here there were two sudden changes of Temperature and Specific Gravity in a few 

 hours. The correction for Temperature has not been applied to the Specific Gravity 

 observations ; it would have increased the difEerenca between those of the warm and 

 cold water. 



