July 27, 1893] 



NATURE 



293 



volume of an already existing publication. I feel that it ought 

 to be in some neutral, or non-society journal, to avoid 

 arousing jealousy. If either the Royal or the Physical Society 

 could take the matter up and arrange for, say, an extra half- 

 yearly number or an extra annual volume of the Phil. Mag., 

 the thing could be done. 



If they could also at the same time arrange for a prompt transla- 

 tion and republication of important foreign papers, many of us 

 would be grateful ; cash has hitherto been the main difficulty, but 

 perhaps with the abundant funds at present available across the 

 Atlantic, we may hope for something large and cosmopolitan in 

 this direction belore long from our co-linguists there. I commend 

 this to the notice of the energetic secretary of the Smithsonian 

 Institution. Everything tending to mitigate the miserable evils 

 of the confusion of tongues would be eminently welcome, and 

 whenever the whole earth has again the happiness of being "of 

 one language and of one speech," I trust that that speech will be 

 English. Oliver J. Lodge. 



The publication of a digest of the scientific papers which 

 have appeared in the English language during even a limited 

 period would entail serious difficulties. In the first place, the 

 expense of printing would be considerable, and it would also be 

 hardly possible to obtain the services of men competent to per- 

 form the task without paying them an adequate fee. In the 

 second place, a satisfactory digest could not be published with- 

 out the cooperation of the various scientific societies ; and every- 

 body who has had any experience as a member of the govern- 

 ing body of any club, society, or other institution is well aware 

 of the difficulty of getting a dozen men, many of whom repre- 

 sent conflicting interests, to agree upon any definite scheme. 



Still, I believe that the foundations of a scheme, which would 

 be capable of development, might be constructed on somev/hat 

 the following lines : — 



In 1889 the London Mathematical .Society printed an index of 

 all the papers published in the first twenty volumes of their 

 Proceedings. The authors were arranged in alphabetical order, 

 and their communications according to the dates of publication. 

 This index will no doubt be brought up to date and reprinted, 

 and I shall suggest (if I am then a member of the council) that 

 an index of suijecls shall also be printed, consisting of two parts 

 viz. pure and applied mathematics, arranged in alphabetical order 

 as regards subjects. Now if every scientific society which deals 

 with pure and applied mathematics, or with experimental sub- 

 jects which are capable of mathematical treatment, would co- 

 operate with the London Mathematical Society in publishing an 

 index of their own papers, arranged, printed, and paged in the 

 same manner, it would be quite easy, by a rearrangement of the 

 type, to print a joint index of all papers on these subjects which 

 have been published, during the last twenty or thirty years, by 

 the societies which co-operate. Each society would bear the 

 expense of printing the original index of its own proceedings ; 

 and a proportionate part of the expense of printing and publish- 

 ing the joint index, together with the profits derived from its 

 sale, would be borne by a'ld received by each society. It will be 

 observed that the above scheme only contemplates a double 

 index arranged according to authors and subjects, and not a 

 digest ; but every one who has had a little experience in hunting 

 up papers, and also, I may add, law cases, will appreciate the 

 value of such an index. 



The editors of the Law Reports always insert under the title 

 of each case a short paragraph in small print, giving an account 

 of the points of law with which the case deals, from which the 

 triennial digest is compiled ; and if scientific societies would 

 in future require authors to adopt the same course, the para- 

 graph could be put into the index, and would be invaluable. 

 The head-note need not amount to more than a few lines, and 

 should describe the object of the investigation without entering 

 into more detail than is absolutely necessary. 



The various reports of the British Association on the progress 

 of different branches of science contain much valuable in- 

 formation, and some of them might with advantage be printed 

 in the index in a condensed form. 



In conclusion, I would suggest that the governing bodies of 

 the different societies should discuss this matter, and that a 

 committee of delegates from those societies, which approve 

 of united action, should be formed. The delegates ought, 

 however, to be practical men well-versed in business, and able 

 and willing to devote their time to the consideration of this 

 question. A. B. Basset. 



NO. 1239, VOL. 48] 



Birds' Methods of Steering. 



The flight of birds still presents several unsolved problems. 

 How they steer, has never been fully explained. With the naked 

 eye or, still better, with a field glass, many of them can be seen 

 to use their tails, lowering the left or right side according to the 

 direction in which they wish to go. This use of the tail as a 

 rudder is much practised by pigeons, jackdaws, rooks, larks, 

 swallows, housemartins, sandmartins, and I believe, by most of 

 our common birds. Gulls let down a foot on one side or the 

 other, and, no doubt, many other web-footed birds do the same. 

 Still a rook or pigeon that has lost his tail manages to steer well, 

 the chief result of the loss being that he cannot stop suddenly, 

 nor float upon the air, but must take rapid strokes with his 

 wings. What other method, then, has the bird of steering? 

 One fact that bears upon this question can be easily observed. 

 When a bird wishes to turn to the left he moves the centre of 

 gravity of his body and flings himself on his leftside, the right 

 wing pointing upward and the left downward. How does he 

 throw himself into this position ? Most writers say that it is by 

 striking harder with one wing than the other. In turning to the 

 left the right wing would give a vigorous stroke, and so raise 

 the right side of the body more than the left. At first sight it 

 seems as if this explanation could not be the true one, since after 

 a hard stroke the right wing should be lower than the left, which 

 has only given a gentle one, and yet it is the right wing that is 

 raised. But we must not be too hasty in drawing conclusions 

 from this. When the down stroke takes place the wings do not 

 descend far ; the body rises so that the end of the wing appears 

 to have described a much greater arc than it has done in reality. 

 If, then, with the right wing a much harder stroke is 

 given than with the left, the right side of the body will 

 at once be raised, and the whole bird will be thrown upon its 

 left side, while the movement of the wing itself may not be 

 enough to be perceptible. If birds are watched as they fly, nne 

 wing seems always to be at the same angle to the body as the 

 other, so that a straight line connecting the tips of the wings 

 would pass through the two shoulder joints, or be parallel to a 

 line passing through them. Instantaneous photographs of birds 

 on the wing seem to me to bear this out. One wing may point 

 up and the other down, but that is through the swaying of the 

 whole body to one side or the other. In spite ot this there 

 may be an inequality of stroke that escapes detection, and with- 

 out assuming this it seems on first thoughts difficult to account 

 for the extraordinarily rapid turns made, for instance, by the 

 swallow. But suppo>ing that what appears to be the case is 

 really so, viz., that equal force is put into both wings, there 

 remains another possible explanation of this movement of the 

 centre of gravity to the left or right in turning. If a bird wishes 

 to steer leftwards, he may bend at the waist towards the left. 

 So much has been said about the rigidity of the bird's backbone 

 that its suppleness at a point just anterior to the ilium has been 

 overlooked. I find that a swallow's vertebral column will bend 

 at this point so as to form an angle of 150° ; in the case of a 

 kestrel it is 156°, of a tern 155°, ofa sandmartin much the same 

 as in the case of the swallow, in the case of a duck 165° ; i.e. a 

 duck can' bend much less at the waist than the other birds 

 mentioned, and you have only to watch ducks on the wing to 

 see that ihey are very poor steerers. This is but meagre 

 evidence, and, at present, I have not the means of collecting 

 more. Si ill, as far as it goes, it seems to show that suppleness 

 of waist goes along with the power of swerving rapidly, and, a 

 priori, it seems extremely improbable that such a highly acro- 

 batic feat should be performed without calling into play every 

 power that is available. Direct observation can, I fear, afford 

 little help, since the feathers obscure any slight bend in the 

 batk. But the habit that many birds have — it can be easily 

 seen in the case ofgulls— of turning their heads in the direction 

 in which they wish to go, suggests that it may be by bending 

 the vertebral column at a point where it would be more effective, 

 that they make their turns, just as a skater changes edge and 

 flies off on an opposite curve by swaying the weight of his 

 shoulders across to one side or the other, a change of balance 

 effected by a bend sideways at the waist. It is certain that birds 

 do not depend entirely on movements of the head or neck, since 

 gulls, for instance, may occasionally be seen to turn to the left 

 while looking to the right and vice versa, a point which may 

 be made out from instantaneous photographs. I cannot help 

 thinking, then, that a bird avails itself of the suppleness of its 

 waist 10 alter its balance when it wishes to turn. Whether this is 

 the sole means, or whether at the same time the wings are worked 



