October io, 1912] 



MATURE 



!61 



led to difficulties when the travellers settled down 

 upon the Centaurian planet; and eventually the 

 party returned to the earth again to find that it had 

 not been annihilated, the new star havini^' passed 

 outside our system. 



There is, of course, a love story to give human 

 interest to the adventures ; and some amusing and 

 exciting episodes lighten the monotony of a tire- 

 some journey. As an attempt to combine fact 

 with fiction, the story is not without merit ; but 

 the style is commonplace, and such a split infini- 

 tive as "to quietly and unostentatiously do" is 

 enough to make anv lover of good literature 

 shudder. ' " R. A. G. 



Catalogue of the Periodical Publications in the 

 Library of the Royal Society of London. Pp. 

 viii + 455 (London: Printed for the Royal 

 Society at the Oxford University Press and 

 sold by Henry Frowde, 1912.) 

 Catalogue of the Periodical Publications, including 

 the Serial Publications of Societies and Govern- 

 ments, in the Library of University College, 

 London. By L. Newcombe. Pp. vii -1-269. 

 (Oxford : Printed for University College, 

 London, by Horace Hart, 1912.) 

 The general plan of both these catalogues is 

 similar, and this is natural, since the Royal Societ)' 

 catalogue has been compiled by Mr. Newcombe, 

 sub-librarian of University College, London, and 

 Mr. L. Ellston. 



.\ catalogue of periodical publications in the 

 library of the Royal Society was last printed in 

 1881, and the large number of accessions to this 

 section of the library in the succeeding thirty 

 years rendered a new catalogue imperative. 

 Instead of adopting the plan of the old catalogue, 

 with its classification under eight separate 

 alphabets, the present has been arranged under 

 one alphabet and restricted as closely as possible 

 to periodical works. 



The catalogues will prove invaluable to scientific 

 ■workers who make use of either library, for the 

 task of discovering a volume has certainly been 

 made as light as possible. 



Bacon's New Globe with- Contour Colouring. 



Natural Scale 1/37,000,000. Price 25s. 

 The globe is nearly fifteen inches in diameter, 

 weighs about four and a half pounds, and is con- 

 sequently easily portable. It is provided with a 

 brass graduated semi-meridian and a conx'eniently- 

 arranged compass. The colour scheme is based 

 on that of the International Map Committee, and 

 the relative land levels and sea depths are both 

 indicated. 



The large number of names included has made 

 the size of type very small, and few places can be 

 read even at a short distance. This will interfere 

 with the use of the globe for class purposes. For 

 individual study the globe will prove useful, and 

 its use may be recommended to correct the wrong 

 impressions formed bv an exclusi\'e examination 

 of flat maps. 



NO. 2241, VOL. 90] 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for 

 opinion" expressed by his correspondents. Neither 

 can he underlake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any oilier part of Naturb. No notice is 

 taken of anonymous co)nmunications.] 



Sailing Flight of Birds. 



Coming out from Queenstown on September lo on 

 her way toward Boston, the ss. Arabic was accom- 

 panied foi- some hours by a large flock of gulls. For 

 the most part these birds were visibly working, flap- 

 ping their wings, but occasionally a few would cease 

 flapping and merely sail along for considerable dis- 

 tances, keeping up with the ship or even gaining upon 

 it, sometimes descending, sometimes ascending, ap- 

 parently at will, with no perceptible action of their 

 wings except, now and then, a slight effort which 

 seemed to be needed for preserving equilibrium, not 

 for support or for propulsion. The wind was of such 

 direction and velocity that the smoke from the ship's 

 funnel went astern in a trail making an angle of, 

 perhaps, 30° with the keel. 



Having at first no reasonable theory of the sailing 

 which the gulls practised, I watched them intently for 

 some time, and made the following observations : — 



(i) The sailing occurred almost wholly, if not quite 

 so, over or near the windward side (the starboard) 

 of the ship, at moderate heights, 20 to 40 ft. perhaps, 

 above the level of the uppermost deck, and not very 

 near the bow. 



{2) When a bird was sailing parallel to the course 

 of the ship, the line from beak to tail was very nearlv, 

 if not quite, parallel 

 to the trail of smoke 

 from the funnel. If 

 the gull turned so as 

 to make his own axis 

 more nearly parallel to 

 the keel of the ship, 

 he drifted to leeward ; 

 if his axis was turned 

 somewhat farther 

 from the direction of 

 the keel than at first, 

 he went to windward. 

 Apparently the head and neck served as a bow rudder 

 for small' changes of direction, the whole body soon 

 following the course indicated and nutiated by this 



^^h.) When a bird was sailing along with the ship 

 his head was held rather low. If he raised his head 

 and lowered his tail, he was carried to leeward or 

 astern with great velocity; this frequently happened, 

 for it was eVident that most of the food was dis- 

 covered bv the gulls behind the sailing ones, and the 

 o-reater part of the flock was usually there. 



(4) When, through a shift in the wind or in the 

 course of the ship, .the smoke began to trail out nearly 

 astern, a change which occupied a few minutes only, 

 the sailing of the birds ceased, each one being then 

 obliged to make visible effort to keep up with the 



\n explanation of the ability of the birds to sail, 

 under the conditions described above, is, 1 believe, 

 found in the upward course of the wind which has 

 struck the weather side of the ship and must rise in 

 order to pass over it. Given a brisk, steady, upward 

 current of air, a gull, with its highly practical kiiow- 

 ledge of mechanics, can, of course, sail in any direc- 

 tion. Tbu«. in the figure here given, if «'w repre- 

 sents -A wing-plane, D the direction of the current of 



