46 
FROM BERMUDAS TO CAPE OF GOOD HOPE. 
—had vanished, together with the burning skies of the tropics. An intended exploration 
of the little-known group of Trinidad Island and Martin Vaz Rocks, situated on the 20th 
parallel, had to give way to the necessities of the moment; but we found time to verify the 
great depth (three miles) of the oceanic valley which closely follows the coast of South America 
from the mouth of the Rio de la Plata to Cape S. Roque. When in about lat. 30° S., Father 
Neptune gave us a severe shaking, leading us some seventy miles out of our course. This 
happened on the 6th and 7th of October. At daybreak of the 14th I was called on deck to 
look at a snow-clad pyramid which rose out of the sea to the southward. It was the peak of 
TRISTAN D’AGUNHA, 83 OO FEET. 
Tristan dAcunha, then fifty miles distant. Whilst admiring this famous landmark of the 
mariner in the South Atlantic, I became aware of a sudden change in the climate. During 
our several cruises from one hemisphere to the other—the “Challenger” crossed the Equator 
six times—we had frequent opportunities of observing the rapid transition from a warm to a 
cold climate, and vice versa. It seems that the atmosphere, like the ocean, is divided by its 
currents into more or less sharply-defined areas of high and low temperature ; and just as in 
the one case a few hours’ sail may carry a ship from the warm waters of an equatorial current 
into the cold stream of an Arctic current, so does a day’s journey often transport a traveller 
from the genial domain of equatorial breezes into the stormy kingdom of polar winds. The 
sailor who yesterday was basking on the forecastle in white jacket, straw hat, and bare feet, 
to-day is seen coming down the ladder in dark garments, dripping sou’-wester, and heavy boots. 
His craft, which but a few hours ago was gently gliding through the waters, with studding-sails 
spread out like the wings of a white albatross, now lies a helpless hulk in the trough of the 
sea, vainly struggling against the billows under double-reefed topsails. 
On the 15th October, H.M.S. “Challenger” arrived off the settlement of Edinburgh, 
so called in memory of the visit of H.R.H. the Duke of Edinburgh in the “Galatea” in 
August, 1867. It occupies the north-west corner of the almost hexagonal island, and is built 
upon a narrow ledge apparently formed by the ddbris accumulated at the foot of the table-land 
which, at a height of 2000 feet, supports the volcanic cone of Tristan d’Acunha. The colony 
boasts of about a dozen huts, with from sixty to seventy inhabitants, and was founded, as 
may be remembered, by a soldier who formed part of the English garrison stationed here at 
the time of Napoleon s exile in St. Helena. Some of the men and women are half-caste. 
They rear cattle, sheep, and poultry, grow a few vegetables, and exchange these productions 
for other commodities with whalers and traders who occasionally call at the island. A 
waterfall which pours over the cliff in front of the settlement affords an abundant 
