590 



NATURE 



[February 5, 1920 



this difficulty can be removed, the kind of flying 

 which the future demands and other countries can 

 give can never be learnt or practised in this 

 country. 



The first need is for some means of flying steadily 

 through thick cloud, either for the purpose of 

 climbing above it, or to approach through it nearer 

 to the destined aerodrome. This problem has 

 lately been solved by the invention of a "turn 

 indicator " which enables the pilot, whether he 

 can see the ground or not, to know when the 

 machine is being flown straight, and it has the 

 valuable effect of allowing the readings of the 

 compass to be relied on; so the gain is double. 

 But in addition to this it is necessary to provide 

 close co-operation with the ground whenever it 

 is wholly or partially fog-enshrouded. The pilot 

 must be told whether his intended aerodrome is 

 fog-free, and, if not, what other aerodromes 

 near his route are sufficiently clear of fog to be 

 safe havens ; this will presumably be by means 

 of some increased efficiency in the wireless tele- 

 phone. Next to this in importance is some means 

 of indicating or conveying to the pilot his height 

 above the ground that happens to be immediately 

 below his machine. These and other such aids 

 are the kind of requirements needed to make all- 

 the-year-round flying possible in this country. 

 It is only a part of the wide field for research, but 

 it is of vital consequence, and it certainly needs 

 (as it is, of course, receiving) Government sup- 

 port, since the immediate financial reward of 

 success must be slight. Moreover, the work is 

 one of public utility, and should be so treated. 



Force is lent to what is here urged by the con- 

 sideration that the air fleet to be maintained by 

 the Government in the near future is so small 

 that it is only by calling in the aid of private 

 craft that the possible needs of an emergency 

 can be met. For this economical procedure to 

 prove a success it is necessary that civil air- 

 craft should exist in sufficient numbers. To facili- 

 tate this calls for the encouragement of all who 

 have ability to assist in making flying safe, in 

 making it popular, in making it efficient. 



PHYSIOLOGY OF MUSCULAR EXERCISE. 



The Physiology of Muscular Exercise. By Prof. 

 F. A. Bainbridge. (Monographs on Physiology.) 

 Pp. ix-t-215. (London: Longmans, Green, and 

 Co., 1919.) Price los. 6d. net. 



IT may reasonably be doubted whether any two 

 physiologists would deal with the subject of 

 muscular exercise along similar lines, nor is it 

 desirable that this should be so, the subject being 

 NO. 2623, VOL. 104] 



so complex and presenting so many different points 

 of view. A comparison of the present volume 

 with the writings of thirty years ago on the same 

 subject is an instructive demonstration of the fact 

 that physiology, as regards certain of its branches 

 at least, has in the course of a generation reached 

 a stage at which experimental results begin to 

 show an integrative connection with problems of 

 a broad and complex nature. 



It is with the wonderful co-ordination of func- 

 tions which is displayed in muscular exercise that 

 the book chiefly deals. The energy usage of the 

 body in exercise may be from eight to twelve 

 times that during rest, and of this about one- 

 third may, in the most favourable circum- 

 stances, appear as work; this energy is ultimately 

 supplied by oxidation, chiefly of carbohydrates, 

 and the central point of the problems of the physio- 

 logy of muscular exercise is that the muscles sud- 

 denly demand from the blood a supply of oxygen 

 which is from ten to twelve times what they 

 receive when at rest. " If the body is to worjc 

 efficiently and to develop its physical powers to 

 their full extent, it is absolutely essential that the 

 movements of the muscles on the one hand, and 

 the activities of the circulatory and respiratory 

 systems on the other hand, should be co-ordinated 

 and integrated into a harmonious whole "' 

 (pp. 3-4). 



The complex co-ordination of circulation and 

 respiration is to a great extent effected by the 

 central nervous system, though the heart and 

 blood-vessels are to some extent autonomous. 

 Chaps, ii. to vii. deal with an analysis of the 

 changes by which the blood and the organs of 

 circulation and respiration are adapted to their 

 several needs. The heart is itself a muscular 

 machine working with a gross efficiency of 

 20-30 per cent., and the adaptation of this organ, 

 is very fully discussed. This is important, since, 

 in ordinary circumstances, it is the working 

 power of the heart which is the limiting factor to 

 the amount of exertion which is possible in any 

 individual; though training may improve the heart, 

 "no man can be an athlete who does not possess 

 a powerful (i.e. a muscular) heart." At high alti- 

 tudes, on the other hand, the limiting factor seems 

 to be the rate at which oxygen can diffuse through 

 the pulmonary epithelium into the blood. 



In the eighth chapter the manner of the exact 

 balancing of the various partially autonomous 

 systems by means of the central nervous system 

 is discussed, and it is shown that, as in so many 

 other instances in the body, the promptness in 

 response to altered conditions is owing to the con- 

 trol of the central nervous system, while the 

 coarser adjustment is effected by the influence of 



