history of our globe, there are some which baffle comprehension. In a certain sense evolution itself may be said to baffle comprehension, since the human intellect can never fully understand how one thing can become anything else; but the general processes of evolution are at least illustrated by facts which long and repeated experience has rendered very familiar. On the other hand, there is nothing analogous to any well-established human experience in the miraculous interference which those have to postulate who either reject evolution altogether, or only recognize it to a limited extent.
Our correspondent also objects to our statement that "all persons with any pretensions to education or intelligence believe in evolution as applied to the physical history of our globe." At the moment we were thinking more of the globe itself than of its living inhabitants; and before objecting to our statement our correspondent might properly have raised with himself the question whether we meant more than we actually said. However, on points like these there will, of course, be differences of opinion, and we must only ask our correspondent to believe that we meant no disrespect in anything that we said to persons of his way of thinking. We believe in evolution because it has already explained so many things, and because its scope as a scientific theory is continually widening. If our correspondent declines to accept it on such grounds as he alleges in his article, he is quite within his right. What he has not shown us is what phenomena or events to which the doctrine of evolution has no application he really understands.
My Canadian Journal, 1872-'78. By the Marchioness of Dufferin and Ava. New-York: D. Appleton & Co. Pp. 456. $2.
The Journal consists of extracts from letters written home to the author's mother while Lord Dufferin was Governor-General of Canada. Although—the letters having been written from twelve to twenty years ago—it is rather an account of the past than a description of the present, and Canada has undergone a great development, its villages having become towns and new railways having developed cities in what was the wilderness, the Journal has lost none of its freshness; for it is the record, made on the spot and at the moment, by a keen observer of cultivated intelligence, disposed to make the best of everything that she saw and experienced; and such records are always fresh. So we are given, in the familiar style which intimate friendship authorizes, yet always graceful, sketches of travel, adventure, scenery, society, social and economical conditions, sports, more serious occupations, and whatever is of the life of the country. The pictures are of all seasons through eight years; they cover all parts of Canada, the St. Lawrence, the lakes, the Maritime Provinces, the west, northwest, and Pacific coast, and the Eastern Townships, with occasional excursions into the United States, concerning which the author is sorry to pass so lightly over the cordiality and the friendliness that were invariably shown her and her husband—"for whether we were traveling officially through Chicago or Detroit, or went as ordinary visitors to New York or Boston, we were always received with a kindness and cordiality which we can never forget."
Studies in Aërodynamics. By S. P. Langley. Smithsonian Institution. 1891.
This monograph of Prof. Langley is the record of four years' experimental work with the inclined plane, to determine the conditions to be complied with in moving such a plane through the air, the power required, etc. His work has thoroughly convinced him of the practicability of moving such planes through the air with our present means of propulsion. It has generally been thought that the one essential element needed to be provided, in order to make mechanical flight possible, was an extremely light and powerful motor. But Prof. Langley's experiments have shown that we need not make a search for such a motor, as the steam-engine, in the forms we now possess it, is quite equal to the occasion. His ex-
