ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxxvii 
interruptions usually produced by land. According to the seasons 
so must the icebergs float, little altered in general form, to different 
distances from the barriers, many of them capsized with their load 
of mud, sand, gravel and blocks uppermost. A large tabular mass 
of ice about three-quarters of a mile in circumference was seen float- 
ing, 130 feet above the water, in about latitude 58° 36'S. As the 
icebergs passed into regions where the decay, in the atmosphere, of 
the higher portions of them became more considerable than of those 
beneath, they would cease to upset, and would carry their loads of mud 
and stones uppermost or below, according as they may have been 
upset more than once by remaining a sufficient time within the need- 
ful conditions. 
Whenever opportunities occurred, Sir James Ross was indefatigable 
in trying for soundings and the temperature of the sea at different 
depths. The results are highly valuable. He was enabled to ascer- 
tain that a belt of sea of uniform temperature, from its surface to the 
greatest depths, extends round the southern regions in a mean lati- 
tude of about 56° 26’. Though this may be the mean, it was found 
to vary in position from 58° 36’ in longitude 104° 40' W. to 54° 41’ 
in longitude 55° 12' W., being a difference 3° 55! of latitude. Such 
variations are to be expected from local causes, and even in the same 
locality from modifications due to great changes of seasons. Sir 
James Ross points out that this belt forms a barrier between two 
great thermic basins, the temperature of 39°'5 (that of the most 
dense sea-water according to the observations made during this 
voyage) descending on the north of it to the depth of 3600 feet in 
latitude 45° S., and in the tropical and equatorial regions to that of 
- 7200 feet, the surface temperature being 78°, while in latitude 70°S. 
the line of uniform temperature descends to 4500 feet, the surface 
temperature being 30°. 
When we compare the distances with the depths of uniform tem- 
perature here noticed, and assume, for the sake of easy illustration, 
a level plain from the equator to latitude 70° S., we find that from 
the surface belt of 39°-5, the inclination of this line of temperature 
would be to the equator on the one side about 1 in 1723, and to 
latitude 70° about 1 in 1136 on the other. Thus the slopes would 
be most gradual, and the depressions on the north and south so 
slight compared with the distances that a tolerably long section 
would show these two thermic basins as slight depressions, and in 
a section less long as scarcely distinguishable from a thick line. 
With such a section before us we experience little surprise that 
the tendency to occupy the same relative level, from the greatest 
density, should be greatly modified by the atmospheric influences on 
the surface of the ocean. 
These observations respecting a belt of uniform temperature in the 
ocean in the southern hemisphere would lead us to anticipate that, 
similar causes being in action in the northern hemisphere, similar 
results would be found there, though no doubt modified by the pre- 
valence of land in the north as compared with the south. The tem- 
perature of 39°°5, obtained by Sir James Ross for the apparent 
