\[{ INTRODUCTION. 



direction to the southeast, and continued through a distance of fifty 

 miles. I make mention of these facts, as it seems to me to go to prove 

 that the barometer, on the margin of these hurricanes, falls, and conti- 

 nues depressed until they have passed. I have carefully examined for 

 records of a gale at this period, but have nowhere met with any notice 

 of one. The depression of the barometer, within the tropics, as before 

 remarked, continued until we passed to a higher latitude, and reached 

 the longitude of 45, when it rose and continued to oscillate remark- 

 ably above 30 in., as will be seen by the diagram on Plate XXI., page 

 700. Until our arrival at the Cape of Good Hope, the temperature of 

 the air varied from 79 to 65, between the latitude of 10 and 34 

 south, nearly -5 to each degree of latitude. It will be seen by the 

 diagram that it was generally a few degrees colder than the water. 

 The variation in the temperature of the water a few days before our 

 arrival, and when near the Cape of Good Hope, shows the existence 

 of the cold and warm currents, which have a remarkable effect upon 

 the climate of the Cape; of this I have made mention in the Narra- 

 tive, to which I would refer for the particular observations on the tem- 

 perature of the ocean ; the diagram also exhibits these variations very 

 forcibly. The rain which fell upon this passage amounted to 2 - 37 in. : 

 it was experienced in the first part of the passage, and continued until 

 we passed beyond the northwest monsoon, or to the northward of 15 

 south latitude, and east of 100 east longitude. The temperature of 

 the rain was 76, the temperature of the atmosphere being at this 

 time 82. I would also refer to the phenomena, of frequent occurrence 

 to the eastward of the Cape, of heavy thunder-gusts, and the pecu- 

 liarity of their enveloping one half of the eastern sky : the beauty of 

 these phenomena is very striking, affording under a bright sunshine and 

 delightful atmosphere a view of the storm-clouds occupying one-half 

 the firmament, while the forked lightnings, and the roaring thunder, 

 were almost incessant. The same phenomena may be met with near 

 the Gulf Stream, and are probably engendered by the same causes. 

 Near the Cape, the warm tropical currents are well defined, and it is 

 on their edge that these remarkable appearances occur. From the 

 information I received, they are local in their character, or confined to 

 the edge of the tropical currents. 



CAPE or GOOD HOPE. Cape Town is not a suitable locality to 

 afford correct meteorological data, situated as it is under the Table 

 Mountain, and in a country so variable in surface as South Africa. 

 It would be difficult to find any position which would represent the 



