Page:A Voyage of Discovery and Research in the Southern and Antarctic Regions Vol 2.djvu/429

1843.

The mean pressure and the amount of atmospheric tide in each latitude are as follows:—

Lat.	Pressure.	Tide.
At the Equator.	29.974	.047	At sea.
13°  0′ S.	30.016	.060	{{{1}}}„
22 17	30.085	.053	{{{1}}}„
34 48	30.023	.052	Cape of Good Hope and Sidney.
42 53	29.950	.050	Van Diemen's Land.
45  0	29.664	.031	At sea.
49  8	29.469	.040	Kerguelen and Auckland Islands.
51 33	29.497	.032	Falkland Island.
54 26	29.347	.022	At sea.
55 52	29.360	.027	Cape Horn.
60  0	29.114	.024	At sea.
66  0	29.078	.016	{{{1}}}„
74  0	28.928	.016	{{{1}}}„

The above results are arranged in belts of latitude, the observations at sea being separated from those made in harbour; this occasions more apparent irregularity than would have been the case had they been formed into two distinct tables.

It has hitherto been considered that the mean pressure of the atmosphere at the level of the sea was nearly the same in all parts of the world, as no material difference occurs between the equator and the highest northern latitudes. At Melville Island in latitude 74¾° it was found to be 29.870, at Igloolik in latitude 69°, 29.770; and at Winter Island in latitude 66° 11′, 29.798. The cause of the atmospheric pressure being so very much less in the southern than in the northern hemisphere