VII,] 
INCREASE OF THE MASS OF OUR GLOBE. 
331 
by M. Tissandier in Paris, and during Nares’ English Polar 
Expedition. 
It may appear to many that it is below the dignity of science 
to concern one’s self with so trifling an affair as the fall of a 
small quantity of dust. But this is by no means the case. For 
I estimate the quantity of the dust that was found on the ice 
north of Spitzbergen at from O’l to 1 milligram per square 
metre, and probably the whole fall of dust for the year far 
exceeded the latter figure. But a milligram on every square 
metre of the surface of the earth amounts for the whole globe 
to five hundred million kilograms (say half a million tons) ! 
Such a mass collected year by year during the geological ages, 
of a duration probably incomprehensible by us, forms too im¬ 
portant a factor to be neglected, when the fundamental facts of 
the geological history of our planet are enumerated. A con¬ 
tinuation of these investigations Vv^ill perhaps show, that our 
globe has increased gradually from a small beginning to the 
dimensions it now possesses ; that a considerable quantity of the 
constituents of our sedimentary strata, especially of those that 
have been deposited in the open sea far from land, are of cosmic 
origin ; and will throw an unexpected light on the origin of the 
fire-hearths of the volcanoes, and afford a simple explanation of 
the remarkable resemblance which unmistakably exists between 
plutonic rocks and meteoric stones.^ 
On the 14th August, when the fog had lightened a little, we 
got up steam, but were soon compelled to anchor again in a bay 
running into Taimur Island from the north side of Tainiur 
Sound, which I named Actinia Bay, from the large number of 
actinia which the dredge brought up there. It is, besides, not 
1 Namely, by showing that the principal material of the plutonic and 
volcanic rocks is of cosmic origin, and that the phenomena of heat, which 
occur in these layers, depend on chemical changes to which the cosmic 
sediment, after being covered by thick terrestrial formations, is subjected. 
