James Croll

“ Were we at liberty to make any assumptions we choose in reference to the smallness of the molecules of matter and their distance apart, we might be able to satisfy the conditions of Le Sage's theory as to mass ; but this we are not at liberty to do. Modern physics has enabled us to determine, at least roughly, the size of the ultimate molecules of matter and also their distance apart. ”

“ It is a necessary condition of Le Sage's theory, in order that gravity may be proportional to mass, that the total volume of the free spaces in a substance in the form of interstices between the molecules must be great compared with the total volume of matter contained in the molecules themselves. ”

“ The number of molecules in a cubic centimetre of a liquid or a solid may, he says, be from 3x1024 to 3x1026. This gives the distance from centre to centre of two consecutive molecules to be from 1/140.000.000 to 1/460.000.000 of a centimetre. ”