periments have demonstrated the somewhat remarkable fact that the power required to sustain an inclined plane, when inclined at a slight angle to the horizontal and driven forward, decreases with the speed. He finds that there is a speed for any given plane at which the plane becomes self-supporting, or rather in which it tends to rise. This speed he terms the soaring speed, and when it is reached the weight becomes unimportant. With greater weights it is only necessary to drive them at greater speeds in order to eliminate the element of weight. The practical conclusion from this is that we are not prohibited by the weight of our apparatus from achieving mechanical flight, and the problems to be solved are not those connected with the question of weight, but rather those concerning the details of construction by means of which the apparatus may be controlled while under movement and in ascent and descent, so as to be safe and manageable. The method of experiment adopted by Prof. Langley consisted in mounting an inclined plane at the end of the arm of a whirling table sixty feet in diameter. This table was driven by power at such a rate that a speed of one hundred miles an hour could be attained. The plane was mounted in such a way that it was free to fall, and, by a number of ingenious appliances designed by Prof. Langley, the power which would be required to drive the plane in free air at the speeds attained could bo measured. The numerical result arrived at by the experiments is that by the expenditure of one horse-power a weight of two hundred pounds can be transported through the air at the rate of forty-five miles an hour. As a steam-engine of this power can be built to weigh not more than one tenth of this amount, it will be seen that there is a wide margin between the weight of the motor and the total weight which can be moved by it. When we consider the vast practical results which would follow the successful navigation of the air, the value of experiments such as these which supply us with data necessary to a solution of the problem can not well be overestimated. It is to be hoped that Prof. Langley will be able to continue his experiments until all the problems bearing upon this interesting and important subject shall have been solved.
The Journal of Physiology. Edited by Michael Foster. Cambridge, England: Cambridge Engraving Company. Vol. XII Price, $5 a volume.
The editor has the co-operation in conducting this journal—the foremost one of its class—of Professors W. Rutherford and J. Burdon-Sanderson, in England, and Professors H. P. Bowditch, H. Newell-Martin, H. C. Wood, and R. H. Chittenden, in the United States, The journal is published in numbers which appear not at rigidly fixed times, but at varying intervals, determined by the supply of material. The present volume consists of five numbers, the last one of which is made up of parts five and six, and contains thirty-one articles in original experimental physiological research. These articles relate to different elements of animal organisms; to the circulation, the nervous system, the action of various substances on bodily functions and products; respiration, temperature relations, the excretions; and to apparatus. They are prepared by careful and accurate experimenters, many of whom are experts or physiologists of world-wide reputation, and record in minute detail what they have themselves observed; the observations being usually accompanied by charts showing the graphic records made by the instruments used.
A Popular Hand-book of the Ornithology of the United States and Canada. Based on Nuttall's Manual. By Montague Chamberlain. Boston: Little, Brown &-Co. Two volumes. Pp. xlvii + 473, and vii + 431. Price, $8.
The first volume of Nuttall's Manual was published in 1832, and the second m 1834. The book was the work of a master of the ornithological knowledge of the day, and of an author who commanded a warm literary style with fine powers of description. It was the first hand-book of the subject that had been published, and was carried at once into favor, not less by its innate qualities than by the interest of the subject. While a great advance has been made in scientific or technical ornithology, the study of bird life, the real history of our birds, remains just about where Nuttall and his contemporaries left it. We have brilliant and engaging essays on various aspects of it by such writers as Bradford Torrey, Mrs. Miller, and
