of Gibraltar, in the neighbourhood of Sicily and
Italy, and in the Grecian Archipelago, we should recommend the
three-hourly series, as marking more distinctly the effects resulting
from the proximity of land; this remark has especial reference to the
passage through the Straits of Gibraltar, where, if possible, hourly
observations should be made.

_The Indian and Southern Oceans. Outward and homeward bound._--On
sailing from the Cape of Good Hope to the East Indies, China, or
Australia, observations at intervals of three hours should be made until
the 40th meridian east is passed (homeward-bound vessels should commence
the three-hourly readings on arriving at this meridian). Upon leaving
the 40th meridian the six-hourly observations may be resumed on board
vessels bound for the Indies and China until they arrive at the equator,
when the readings should again be made at intervals of three hours, and
continued until the arrival of the vessels in port. With regard to
vessels bound for Australia and New Zealand, the six-hourly readings may
be continued from the 40th to the 100th meridian, and upon the vessels
passing the latter, the three-hourly readings should be commenced and
continued until the vessels arrive in port. Vessels navigating the
Archipelago between China and New Zealand, should make observations
every three hours, in order that the undulations arising from the
configuration of the terrestrial and oceanic surfaces may be more
distinctly marked and more advantageously compared with the Gulf of
Mexico, the Caribbean Sea, and the northern portion of the African
continent.

_The Pacific Ocean._--As this ocean presents so vast an aqueous surface,
generally speaking observations at intervals of six hours will be amply
sufficient to ascertain its leading barometric phaenomena. Vessels,
however, on approaching the continents of North and South America, or
sailing across the equator, should resort to the three-hourly readings,
in order to ascertain more distinctly the effect of the neighbourhood of
land on the oscillations of the barometer, as generally observed, over
so immense a surface of water in the one case, and the phaenomena of the
equatorial depression in the other: the same remarks relative to the
latter subject, which we offered under the head of South Atlantic, will
equally apply in the present instance. The configuration of the western
shores of North America renders it difficult to determine the pr