As already intimated, our knowledge of palaeometeorology, or of past climates, is derivable chiefly from fossils.
The fact that both male and female costume amongst the primitive Aegean peoples is derivable from the simple loin-cloth with additions is rightly used by Mackenzie as a proof that their original home is not to be sought in the colder regions of central Europe, but in a warm climate such as that of North Africa.
Thus Basilides assumed the existence of two principles, not derivable from each other: Light and Darkness.
The process of transvection is connected with the operations 12; for?k (a m b n) = (ab)kam-kbn-k, (x y x y or S 2 k (a x by) x = 4))k; so also is the polar process, for since f k m-k k k n - k k y = a x by, 4)y = bx by, if we take the k th transvectant of f i x; over 4 k, regarding y,, y 2 as the variables, (f k, 4)y) k (ab) ka x -kb k (f, 15)k; or the k th transvectant of the k th polars, in regard to y, is equal to the kth transvectant of the forms. Moreover, the kth transvectant (ab) k a m-k b: -k is derivable from the kth polar of ax, viz.
Iv.) was the first to remark that the study of covariants may be reduced to the study of their leading coefficients, and that from any relations connecting the latter are immediately derivable the relations connecting the former.