70 | REPORT— 1858. 
basin one shock for every 8,000,000 square miles of surface, and, in the Euro- 
pean area, one shock for every 37,500 square miles of surface ; so that within 
these large areas the seismic energy beneath the land is to that beneath the 
ocean-floor as 213: 1 nearly. The annual number of observed European 
earthquakes is certainly below the actual number that occur; and although 
the Atlantic is the only oceanic surface of our globe over which there can 
be a pretence even to correct observation, yet its recorded numbers must 
be very far indeed below the truth, and immeasurably lower in proportion 
than for Europe. Making, however, every allowance for imperfect inform- 
ation in the pelagic area, the disparity of relative numbers is such, as to 
warrant our estimating, with some confidence, that the seismical energy is 
manifested with much greater power for equal areas upon the dry land than 
upon the ocean-bed. 
Should it ultimately prove a fact, as rendered probable from the beautiful 
investigations of Darwin, that there are great areas of gradual subsidence now 
in motion beneath the Pacific, it may still happen (though it is not probable) 
that seismic or even voleanic bands may traverse such areas of subsidence, 
without materially affecting their general downward movement. Although 
many portions of the earth’s surface now show evidences of vertical insta- 
bility, either slowly, or per saléum occasionally, rising or sinking, these effects 
are all comparatively insignificant in extent. The great formative forces, 
whatever they were, upon which the elevated land of the great continents and 
the depression of the ocean-beds depended, have ceased sensibly to act. The 
function of the volcano and the earthquake in the existing cosmos is not crea- 
tive, but simply preservative ; and vast as they appear to eye and sense, their 
effects are very small in relation to the totality of the great terrestrial machine. 
If, however, such large areas of oceanic subsidence as have been supposed 
really exist, they will most probably be found situated almost centrally within 
the oceanic sub-basins, and hence surrounded but not traversed by seismic 
bands. 
There is one fact, which is shown by the relative positions, upon this map, 
of the greatest voleanic areas upon our globe (and these the most active) and 
of the blue-tinted areas of probable subsidence, that is worthy of fixing our 
attention. 
It will be observed that the blue bands of probable subsidence are tole- 
rably adjacent to the greatest seats of volcanic activity, and that the latter 
generally have subsiding areas at more than one side. Thus, in the Pacific, 
the blue band is along the great volcanic girdle from Celebes to New Zealand, 
and thence stretches between (and at one point may cut through) the line 
of suboceanic volcanic girdles, from the New Hebrides to the Marquesas. 
Again, the great volcanic horse-shoe girdle of Sumbava is between the 
blue (subsiding) area in the China Sea north of Borneo, and the blue coral 
bands north of Australia, which whole continent, or at least its western and 
northern parts, may probably be subsiding also. Lastly, in the north we have 
Iceland and its voleanic system, between the sinking coasts of Greenland and 
those of the Baltic. 
If we admit, then, as certain, that these vast tracts are subsiding, we can 
searcely withhold our belief that the subsidences are due to and are the 
equivalent in bulk of the solid ejecta and exhalations of these various great 
volcanic areas respectively. 
The assumed area and extent of subsidence of those supposed subsiding 
tracts are, however, I apprehend, greatly overrated; this, however, is not the 
place to pursue their consideration. 
From all that has preceded (here and in former Reports), it is plain that 
