268 THE VOYAGE OF H.M.S. CHALLENGER. 



occasionally experienced at all seasons. North and northwest gales are not felt much at 

 the settlement, as the wind is then blowing directly against the face of the cliffs at the 

 back, but with these winds there is a heavy surf in Falmouth Bay ; the southwest 

 wind sweeping fairly across the level strip is most destructive, and has been known to 

 unroof the houses, solidly built as they are. The climate is mild, the temperature 

 averaging 68° in summer, and 55° in winter, occasionally falling to 40°. Eain is 

 frequent ; in fact, situated as these islands are, and rising as they do to a height of over 

 7000 feet, it would be extraordinary if rain were not frequent, as clouds almost continuously 

 cover the higher parts of the land. Hail and snow fall occasionally, but rarely, and the 

 sky is usually cloudy, but the air is not excessively humid. Little is known about the 

 movements of the barometer in the locality ; the islanders possess an instrument, but 

 do not record its readings. Captain Wauchope states that during his stay in H.M.S 

 " Eurydice " in the vicinity of the group, the pressure varied from 2975 to 30"35 in the 

 months of October and November 1817 ; but he could form no opinion as to the future 

 condition of the weather from the height of the barometric column. During the four 

 days' visit of the Challenger in 1873, the pressure was unusually great, the mercurial 

 column varying from 30 - 605 to 30 - 233 inches, and the weather, though cloudy, was on the 

 whole fine, the wind being light. That the climate is very healthy is beyond a doubt, 

 for the inhabitants do not appear to suffer much from sickness ; Lieutenant Rich says 

 that they all suffered from inordinate appetites. 



The time of high water, at full and change, is given by Lieutenant Rich as at 2 hours 

 with a rise and fall of 8 feet. Captain Nolloth, in his visit in 1856, made it, high water, 

 full and change, at 12 hours, rise and fall 4 feet, and the islanders state that it never exceeds 

 that, amount. No register has, however, been kept ; and it would be exceedingly difficult 

 to erect a tide pole in a sufficiently sheltered position, although, could it be done, a record 

 here would be of decided scientific value. 



There appear to be some discrepancies in the various accounts given as to the tidal 

 stream or current. Some of the old navigators say that they observed a regular east and 

 west going stream when at anchor in Falmouth Bay. Others say the current always sets 

 to the northeast ; whilst the islanders assert that inshore the stream changes, but that 

 outside the current is always northeasterly. Against this assertion, however, must be 

 placed the fact, that Captain John Patten found a great deal of driftwood on the east coast 

 of the island and none on the west side in 1790. Captain Nolloth was, however, told that a 

 sofa was made on the island from a log of wood (mahogany) that grounded on the west coast 

 of Tristan Island, and says, that at the time of his visit, there was a tree thickly covered 

 with barnacles on " the sea side." This latter observation is, however, rather obscure, as 

 it is difficult to tell which is not a sea side at Tristan. The current experienced by the 

 Challenger whilst in the vicinity had certainly . a northeasterly tendency, but it is of 

 greater force westward than eastward of the group. 



