That the mind of the female sex is capable of compassing great and extraordinary attainments, even in the most arduous branches of science, is attested by many instances; and it cannot be doubted that these would be more numerous, were women oftener attentive to philosophical pursuits. Those who have been just named serve to shew, that astronomy has been cultivated with success, by them. And Dr. Reid tells us (in his _Essays on the intellectual and active Powers of Man_,) that both the celebrated Christiana, Queen of Sweden, and the Princess Elizabeth, daughter of Frederick, King of Bohemia, and aunt of George I., were adepts in the philosophy of Descartes. The latter of these princesses, though very young when Descartes wrote his _Principia_, was declared by that philosopher to be the only person he knew, who perfectly understood not only all his philosophical writings, but the most abstruse of his mathematical works. ----- Let not, then, the beauties of astronomical science, and the captivating studies of natural philosophy in general, be exclusively enjoyed by men; but let the amiable, the intelligent, and the improved part of the female sex, be invited to a participation, with them, in these intellectual pleasures.[45] ----- Footnote 45: The writer is happy in having it in his power to cite, in support of his own opinion, that of an amiable and conspicuous female, in favour of ladies making themselves acquainted with, at least, the rudiments of astronomical science. The Countess of Carlisle, a woman whose literary attainments, as well as virtues and accomplishments, do honour to her sex and station, in her Letters, under the signature of _Cornelia_, thus recommends an attention to the study of astronomy, to the young ladies to whom her letters are addressed. “Attain a competent knowledge of the globe on which you live, that your apprehension of Infinite Wisdom may be enlarged; which it will be in a much higher degree, if you take care to acquire a general idea of the structure of the universe. It is not expected you should become adepts in astronomy; but a knowledge of its leading principles you may, and ought to obtain.”—Her ladyship then refers her young female correspondents to the _Plurality of Worlds_ of Fontenelle, in order that they might acquire a knowledge of the planetary orbs; pleasantly recommending this author as a proper person, in the capacity of “a gentleman usher,” to “introduce” them to an “acquaintance” with “that brilliant assembly.” _Lady Carlisle’s Letters_, lett. 8th. ----- Here, perhaps, might be rested the evidence of the all-important usefulness of that branch of knowledge, in which our American Philosopher was pre-eminently distinguished.