702 



THE POPULAR SCIENCE MONTHLY. 



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 prac- 

 tical 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 connect- 

 ed with the question of weight, but rather 

 those concerning tlie details of construction 

 by means of which the apparatus may be 

 controlled while under movement and in as- 

 cent and descent, so as to be safe and man- 

 ageable. The method of experiment adopt- 

 ed 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 nu- 

 merical result arrived at by the experiments 

 is that by the expenditure of one horse-pow- 

 er 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 con- 

 sider 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 overesti- 

 mated. It is to be hoped that Prof. Langley 

 will be able to continue his experiments until 

 all the problems bearing upon this interest- 

 ing and important subject shall have been 

 solved. 



The Journal of Phtsiologt. Edited by 

 Michael Foster. Cambridge, England: 

 Cambridge Engraving Company. Vol. 

 XIL Price, $5 a volume. 



The editor has the co-operation in con- 

 ducting this journal — the foremost one of its 

 class — of Professors W. Rutherford and 

 J. Burdon-Sanderson, in England, and Pro- 

 fessors 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 vol- 

 ume consists of five numbers, the last one 

 of which is made up of parts five and six, and 

 contains thirty-one articles in original ex- 

 perimental physiological research. These 

 articles relate to different elements of ani- 

 mal organisms ; to the circulation, the nerv- 

 ous system, the action of various substances 

 on bodily functions and products ; respira- 

 tion, 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-nooK of the Ornithology 

 OF the United States and Canada. 

 Based on Nuttall's Manual. By Mon- 

 tague Chamberlain. Boston : Little, 

 Brown & -Co. Two volumes. Pp. xlvii-f 

 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 contempo- 

 raries left it. We have brilliant and engag- 

 ing essays on various aspects of it by such 

 writers as Bradford Torrey, Mrs. Miller, and 



