November 4, 1909J 



NA TURE 



19 



Commenting on the aviation meetings at Doncaster and 

 Blackpool, Engineering for October 22 directs attention to 

 the advantages of the monoplane from the point of view 

 of transport from place to place. The frame consists 

 simply of the backbone carrying the engine, driving-seat, 

 and controlling gear, together with the wheels on which 

 the machine runs when on the ground. This can be sent 

 complete in one piece, the main wings and the horizontal 

 and vertical rudders being detached for the purpose. The 

 wings are attached very easily by means of sockets on the 

 backbone and by wire ties. In the case of one competitor, 

 whose main wings had not arrived until late in the 

 morning, these were all fixed up in about an hour. 

 Probably with more experience it will be possible to 

 design a monoplane which can be taken to pieces or erected 

 complete in an hour or two. The biplane, having more 

 numerous tie-rods, appears to require much larger packing 

 cases or more time for its erection, according to the 

 extent to which it is taken to pieces. In the air the 

 biplanes certainly appear to be more steady than the 

 monoplanes, the latter occasionally flying in a series of 

 dips, especially when near the ground. When high up, 

 however, the monoplane appeared very steady. 



While remarking on the enormous advance which has 

 been made in aviation. Engineering points out that the 

 motors have very far from the trustworthiness required 

 for practical work, and each machine had several 

 mechanics in attendance on it. The engines at present 

 in use require a large amount of attention. This is a 

 matter which should be capable of amendment. The other 

 limitations which require attention are the incapacity for 

 flying in bad weather and for alighting on rough ground. 

 To be of any practical use, aeroplanes should be capable 

 of alighting and starting from an ordinary grass or stubble 

 field, and there does not seem the least difficulty in 

 arranging for this ; in fact, the combination of runners 

 and wheels on the Farman machine would probably be 

 satisfactory. Flying in a wind may possibly be largely 

 a matter of practice and confidence, and it is quite possible 

 that, with very little alteration in the machines, men will 

 learn to fly in any reasonable weather. 



Erratum. In the article upon the magnetic results of 

 the Carnegie (October 28, p. 532, col. 2, line 3 from 

 bottom) Dr. Bauer should have written i" instead of J', 

 which was the value given in the typewritten communica- 

 tion received from him and printed in Nature. 



OUR ASTRONOMICAL COLUMN. 



Changes on Mars. — .Another large prominence on the 

 terminator of Mars is announced by M. jarry-DesIoges 

 in No. 4364 of the Astronomisehe Nachrichten (p. 335). 

 This object was seen on the night of October 14-15 in 

 the region of Phaethontis, which itself was very white ; 

 this whiteness of Phaethontis, and similar regions near the 

 limb, was remarked by the Rev. T. E. R. Phillips in his 

 observations of 1903. 



A drawing of the planet, as it was seen by M. .Antoniadi 

 with an 83-cm. reflector on September 20, is published as 

 a frontispiece to No. 10, vol. iii., of the Rivista di Aslro- 

 nomia (Turin). 



Hallev's Comet. — In No. 4364 of the Astronomisehe 

 Nachrichten (p. 333, October 20} Prof. Wolf publishes the 

 position of Halley's comet as determined from a plate 

 taken on October 10, and states that, with a power of 

 140 used on the reflector, he is able to see the comet as 

 a small nebulous patch ; but it is on the limit of visibility 

 with this instrument, its magnitude being given as 14-5. 



In the same journal (p. 335) Mr. Knox Shaw gives 

 NO. 2088, VOL. 82] 



positions determined from photographs taken at the 

 Hehvan Observatory on September 13, 15, and 16 re- 

 spectively. 



An interesting popular article, dealing with the history 

 and nature of the comet, appears in part cxliii. of 

 Chambers's Journal (p. 710, November i) from the pen 

 of Dr. Alex. W. Roberts. 



Sun-spot Spectra. — A summary of the results so far 

 obtained from the study of the photographs of sun-spot 

 spectra, taken at the Mount Wilson Observatory, is pub- 

 lished by Prof. Adams in No. 2, vol. xxx., of the .4i(ro- 

 physical Journal (pp. 86-126, September). 



The paper is too comprehensive for adequate summary 

 in these columns, where many of the details have already 

 appeared, but the various tables given will prove interest- 

 ing and instructive to all workers in this branch of solar 

 phvsics. 



Prof. Adams believes that the intensification of various 

 solar lines in the spot spectrum is due to the lowering of 

 temperature, and not, in general, to a variation of 

 pressure. Investigations at Mount Wilson, where a shift 

 of 0003 or 0-004 ^- could be detected, indicate that the 

 excess of pressure in spots, over that on the surface of 

 the sun, can hardly be so great as one atmosphere. .\ 

 study of the enhanced lines, based mainly on the tables 

 published by Lockyer, shows that of 144 such lines 130 are 

 distinctly weakened, while fourteen show no change, in 

 passing from the Fraunhoferic, to the spot, spectrum. 



The lines of each element are studied seriatim, and of 

 the lines of iron given by Rowland, 784, or 71 per cent., 

 are affected in the spot spectrum ; of the 558 lines due to 

 iron alone, 300 are strengthened and 258 weakened in 

 passing from the solar to the spot spectrum. The 

 behaviour of the iron lines is best explained by the decrease 

 of temperature in the spot. 



The greater part of the unknown fluting, and band, lines 

 in the spot spectrum may be accounted for by the presence 

 of the titanium oxide, " magnesium hydride," and 

 " calcium -hydride " spectra, whilst the lines that are 

 w-idened without marked increase of intensity are 

 sufficiently explained by the existence of a magnetic field 

 in sun-spots. 



Designations of newly discovered V.-iriable Stars. — 

 The committee for the .A.G. Catalogue of Variable Stars 

 publishes the permanent names of sixty-two recently dis- 

 covered variables in No. 4364 of the Astronomisehe Nach- 

 richten. The provisional name, permanent designation, 

 position, and magnitude range are tabulated for eacfi 

 object, and a series of notes gives particulars of discovery 

 and subsequent observations. 



The Motions of Some Stars in Messier 92 (Hercules). 

 — Prof. Barnard discusses the proper motions of certain 

 stars in the cluster M. 92 in a paper appearing in No. 4363 

 of the Astronomisehe Nachrichten. 



Micrometer observations of this cluster were made by 

 Schultz, at Upsala, about 1873, and results were published 

 for thirty-seven stars. These results, when compared with 

 those obtained from a photograph taken in 1898, led Dr. 

 Bohlin to the conclusion that some of the stars exhibited 

 large proper motions during the twenty-five years' interval, 

 but Prof. Barnard suggested that Schultz 's observations of 

 faint objects with a 9-inch telescope were probably not 

 sufficiently exact to permit of this deduction ; measure- 

 ments of two photographs, taken with an interval of eight 

 years between them, confirm the suggestion. 



There are two stars, however, which show decided 

 motions during the eight-year interval, one being No. 11 

 and the other a fainter star temporarily designated a. The 

 former has an annual motion of 00S5" in position angle 

 220° (8-5" per century), and the second an annual motion 

 of 0065" in position angle 181-4° (6-5" per century). Prof. 

 Barnard concludes that another fifty years should show- 

 motion in many of the stars of this cluster, whilst within 

 a few hundred years it will be possible to investigate the 

 laws which control the motions of this and similar great 

 and crowded masses of stars. A carefully oriented repro- 

 duction of a photograph of M. 92, taken with the 40-inch 

 telescope, accompanies the paper, and will facilitate further 

 work on this interesting cluster. 



