I Snill| II
ii "
the mercury 43°.* Unfortunately the day was very cloudy,
and many squalls of sleet and rain, which obscured the hills,
passed whilst I was taking bearings. To the N.F., towards
the supposed Sebastian Channel, the horizon was too hazy to
allow much view. A deep inlet was seen in that direction;
but whether the land closed round, or whether a channel Avas
at the bottom, we could not distinguish. A considerable body
of Avater Avas observed to the southAvard of Cape St. Valentyn,
behind Lomas Bay, but its extent Avas screened from our view
by the intervention of the Lomas hills. It appeared to be a
cliannel, the opposite or eastern side of it being formed by the
liigli ranges previously seen from Point St. Mary. Cordova’s
Ports San Antonio and Valdez were distinctly made out; but,
to the southward, every thing Avas enveloped in mist.
The bearings and observations, Avhich occupied me nearly
tAvo hours, being completed, Ave all adjourned to a sheltered
cleft in the rock close to our station, where Ave soon recovered
the use of our fingers.i*
* The result of the barometric obsen'ation for the h eight of Mount Tarn
is as follows:
H eight by one b a rom e te rf ¿ e s c eL ^ ’e S - t j ” ^®“ 2,596-.') feet.
Drxo . Xt wo dJ o. Ir adsecsecnetn t 22,:651996’3-7\/ - o caq o
2,602-2
By angular measurement from Observation Cove, P o rt Famine, with
theodolite, allowing of the intercepted arc for terrestrial refraction, the
height is 2,850 feet.
Another observation, with the sextant, made it 2,855 feet. Th e mean
2,852 I consider more correct, from the difficulty of obtaining a correct
reading of the barometer on the summit.
t By Daniell’s hygrometer, used in this sheltered spot, I found the
temperature of the a ir to he 48° ; dew point 41°; but upon exposing the
instrument to the wind, the air was 39^°, and the dew point 36° : the difference
in the former being 7° j and the latter 3^° ; from which the following
results are obtained:
air. dew pt. diff. exp. dryness.
weight o f a cubic,
In the ravine 48 41 7 292 776 3*323
Exposed to wind 39^ 36 3^ 248 898 2*871
Diflcrence 5 44 122 0-452
'I'hc
foot o f air.
43
Having accomplished our object, we began the descent. In
a comparatively mild and agreeable spot, I again set up the
theodolite and barometer, Avhile some of the party employed
themselves in fruitless attempts to kindle a fire. The height,
by the barometer, proved to be 1,845 feet above the sea; and
the bearings from this station were much better than those I
had taken from the exposed summit.
We reached our tent at noon, having been absent scA-en
hours. At three we reached the beach, where the barometer
stood at 29.312 (air 61.°3,* and mercury 62,°5).
Fxcepting near the sea, where clay-slate (very similar to
that of Point St. Anna, but with an opposite dip) shoAA-ed itself,
the side of the hill is clothed Avith trees and underwood, and
no rock is visible until one arrives at the ravine. Around the
summit of Mount Tarn the ground is bare, but so coA'ered with
small decomposed fragments, that the solid rock only appears
occasionally : it is very hard, and breaks with a conchoidal
fracture ; some of the specimens which we detached bore indistinct
impressions of organic remains. We also found, projecting
from the rock in which they were embedded, nodules, or
small rounded masses of stone, in an advanced state of decomposition,
mouldering away in laminar forms somewhat resembling
the inner leaves of a cabbage. Several were brought
aAvay carefully, but before we arrived on board they had crumbled
to pieces : the nucleus was quite hard, but Avas surrounded
by concentric laminae, more brittle the nearer they approached
to the outer surface. It seemed as if the face of the summit
T h e above being the difference in the short space of three feet apart ;
the instrument, in the first case, being ju s t under the lee of the rocky
summit of the mountain, and in the last, above it, exposed to the Avind.
* The air was so dry this afternoon th a t I failed to procure a deposit
of dew upon D aniell’s hygrometer, although the internal temperature Avas
lowered from 61° to 37°. One of Jones’s portable hygrometers was also
tried, and the temperature was lowered to 31°1 Avithout a deposit ; so that,
the difference being more than th irty degrees, the expansive force of the
air must have been less than 212, the dryness, on. the thermometric scale,
less than 367, and tlie Aveight of vapour, in a cubic foot of air, less than
2,355 grains.
Ill;
! :il
* I