CHAPTER XX. 
Valparaiso to Cape Tres Montes — The Cirripedia and Pycnogonida — Through the Messier Channel, Sarniiento Channel, 
and the Strait of Magellan to the Falkland Islands — The Isopoda — The Falkland Islands — Fossils — The Scapho- 
poda and Gasteropoda — The Anomura. 
Valparaiso to Cape Tres Montes. 
On the 11th December, at daylight, the Challenger proceeded outside the ships 
at anchor in Valparaiso Harbour, and was swung to ascertain the errors of the 
compass and dipping needle. At 1.30 p.m. this operation was completed and all sail 
was made on the port tack to a fresh southerly breeze. The day was fine and the 
' atmosphere so remarkably clear, that Mount Aconcagua was seen at sunset quite 
distinctly. 
During the whole passage from Valparaiso to the Gulf of Penas steady southerly 
winds were experienced, never exceeding a force of 5, with fine although somewhat 
cloudy w T eatlier, and a smooth sea. This necessitated beating down the coast to Cape 
Tres Montes, which occupied twenty days (see Sheet 40). On the passage Juan Fernandez 
Island was sighted, but the vessel did not touch there ; four soundings, five serial 
temperature soundings, and three trawlings were obtained. 
The soundings obtained were made into a meridional section in order to show the 
temperatures, but as they were taken at varying distances from the coast, no conclusion 
as to the contour of the bottom can be formed (see Diagram 21). 
The surface temperature was 62 c at Valparaiso and 59° at Juan Fernandez, from 
whence it gradually decreased to 55° in the Gulf of Penas. 
The serial temperatures show that the isotherm of 40° is almost parallel with 
the surface, and that the higher isotherms gradually rise as the surface temperature 
cools. 
The surface current experienced always had a northerly tendency, although the 
daily calculations showed its direction to be sometimes east and sometimes west of 
north. The total current experienced was north 8 miles per day, the easterly and 
westerly deflections almost counterbalancing each other ; the last three days, however, 
when close to the Peninsula of Tres Montes, little or no set was felt, the true rate of the 
northerly current along the coast by the observations being about 9 miles per day. 
The following anemometer observations were taken : — 
