230 KANSAS CITY REVIEW OF SCIENCE. 
sequently under Captain Maclear, has been employed on arduous service, chiefly 
in a critical examination of the ship channels adjacent to the fiftieth parallel of 
latitude. Trinidad channel—directly opening into the Pacific Ocean—with Con- 
ception chanael leading from the inner waters north of Magellan Strait into Trini- 
dad channel, have all been surveyed, together with their numerous ports and tem- 
porary anchorages likely to be useful to passing shipping. Innocentes channel, 
leading to Conception channel from the now well known Guia narrows, has also 
been examined and charted. 
Trinidad channel opens out a clear passage to the Pacific Ocean, 160 miles. 
to the north of Magellan Strait; and although not so secure of approach from 
the Pacific as the well known entrance into that strait by Cape Pillar and the 
Evangelists, it will be found a valuable addition to our knowledge of these waters, 
as enabling ships passing into the Pacific to avoid the heavy sea.frequently ex- 
perienced in the higher south latitude. Similarin feature to Magellan Strait, the 
ocean entrace of Trinidad channel is shoal, having only forty fathoms of water it 
the deepest part, the depths gradually increasing to 300 fathoms in the inner 
channels. The southern shores are bounded by bold, rugged mountains, rising 
abruptly from the sea; whilst on the northern side a low wooded country lies be- 
tween the sea and the rugged spurs of distant snow-clad mountains ; both shores. 
are cut up into numerous bays and inlets. In the latter months of the year very 
few natives were seen; it is understood that at this season the Fuegians leave the 
inner waters for the outer seaboard, in pursuit of seals. 
During the winter months, the Alert, having refitted at Coquimbo, then visited 
St. Felix and St. Ambrose islands, and obtained a series of ocean soundings in an 
area unexplored by the Challenger in 1875 ‘These islands appear to be uncon- 
nected with the South American continent, for soundings obtained midway gave a 
depth of 2250 fathoms (rad. ooze), with a bottom temperature of 33°.5 F , both 
depth and temperature thus corresponding to the general bed of the South Pacific 
Ocean. Neither do they join the Juan Fernandez group, for the depths between 
reached 2000 fathoms. These several scattered lands thus appear to rise from 
a submarine plateau as isolated mountains. Captain Maclear describes St. Am- 
brose Island as volcanic, composed entirely of lava arranged in horizontal strata 
very marked, intersected vertically by dikes of basalt; vegetation is scanty, and 
the island is without water ; though frequented by sea birds, the sides are too steep 
and rugged for guano to collect. 
