320 



NATURE 



[May 12, 1910 



21 inches, in diameter, the stroke being 30 inches. Each 

 cylinder is fitted at each end with separate steam and 

 •exhaust valves of the drop-piston type. A steam engine 

 uses considerably more steam than is shown by the indi- 

 cator to be present in the cylinder at any part of the 

 stroke. This loss has been generally attributed to initial 

 •condensation, but more recently the belief has been held 

 that valve leakage is responsible for much of the extra 

 steam used. It is hoped that the trials upon this engine 

 may be used to supplement the work done in other labora- 

 tories in elucidating this point. Thus the Armstrong 

 ■College engine has slide valves ; the Manchester Municipal 

 School of Technology engines have permitted of work 

 teing done upon Corliss, double-beat drop, and slide valves ; 

 the drop-piston valves fitted to the new Glasgow engine 

 should therefore afford opportunities of making useful 

 comparisons. 



OUR ASTRONOMICAL COLUMN. 



CoMF.TARY Orbits. — Messrs. Crawford and Meyer give 

 new elements for Halley's comet in Bulletin No. 179 of 

 the Lick Observatory, based on observations made on 

 September 17 and December 16, 1909, and February 28, 

 19 10. The perturbations due to Mars in January were 

 found to be ineffective, and the time for perihelion is 

 finally given as April i9^6776o G.M.T. 



When it became known that other computers found 

 great difficulty in computing an orbit for comet 1910a, 

 Miss Levy and Mr. Meyer, of the Berkeley Astronomical 

 Department, decided to test a method devised by Prof. 

 Leuschner. For this purpose photographic observations 

 secured by Dr. Curtis, with the Crossley reflector, on 

 February 1,-2, and 5, were selected, and a very satisfactory 

 result obtained from the direct solution for an approximate 

 orbit. Other observations were then considered, covering 

 the period January 18 to March 13, and final parabolic 

 elements calculated by the same method. These are given, 

 with an ephemeris, in Bulletin No. 179, and the ephemeris 

 Indicates that the comet is still a little west of the Great 

 Square, and is very faint. Observations by Dr. Aitken on 

 April 13 gave corrections of — o-gs. and —4*. Elliptic 

 elements for Daniel's comet, 19096, published by Sturla 

 Einarsson and R. Young in the same Bulletin, give a 

 period of 6-48 years. 



Recentlv published elliptic elements for comet 1910a give 

 periods of 202^6 and 41 years respectively. 



Measures of Double Stars. — No. 175 of the Lick 

 Observatory Bulletins contains the measures of 136 double 

 stars made by Mr. Olivier with the 12-inch and 36-inch 

 refractors of the Lick Observatory. Generally, the stars 

 measured are neglected pairs in the southern hemisphere, 

 such as can be observed from lat. 38° N., or pairs which 

 «how signs of motion. Eleven new doubles are included. 

 and of the 136 stars observed, if; are separated by less 

 than i", 56 between i' and 2", and 30 between 2* and 3". 

 It is interesting to note that the 12-inch refractor was 

 generally employed, and leaves nothing to be desired as 

 regards definition ; a power of either 500 or 625 was alwavs 

 used, and doubles down to o^e' in distance could be readily 

 measured. 



Maximum of Mira, 1909. — Astronomische Nachrichten 

 No. 4403 contains two notes on the most recent maximum 

 of Mira. The first is by Herr May, of the Kasan Observa- 

 tory, who finds that the maximum took place on September 

 0, 1009, the magnitude being 3-14. The second is by Herr 

 T^andwehr, Miinster. and gives September 4^7 and 3^1^ 

 respectively. According to Guthnick's ephemeris, the epoch 

 of maximum was September 6-g, and the magnitude should 

 Tiave been 3-27. 



Parallax of the Planetary Nebula G.C. 4373- — From 

 a photographic determination. Dr. Bohlin finds that the 

 parallax of the planetarv nebula G.C. 4373 (H iv. 37) is 

 — 0-170'' + 0^042 ', and the correction for the aberration 

 constant is —0-043" ±0042" (Astrononiisdie Nachrichten, 

 "No. 4406, p. 232). 



NO. 21 15, VOL. 83] 



HALLEY'S COMET AND METEOROLOGY. 



Proposed Meteorological Observations during Progress 

 through the Tail of Halley's Comet. 



THE International Commission for Scientific Aeronautics 

 had arranged a series of ascents of kites and ballons- 

 sondes for Mav 11-13, but seeing that it is possible that 

 the earth may 'pass through the tail of Halley's comet on 

 May 19, the members of the commission have agreed to 

 postpone the ascents to May 18-20. A circular from Prof. ; 

 Hergesell, the president of the commission, gives par- 

 ticulars of the proposed ascents, the times mentioned being 

 as follows :— Mav 18, 7 a.m. and 10 p.m. ; May 19, 

 2.30 a.m. and 7 'a.m. ; and May 20, 7 a.m. Observations 

 should be made at the earth's surface, and hallons-sondes 

 should be sent up about half an hour before these times, 

 so that the balloon for the principal ascent should reach 

 its greatest height about the time when the earth passes 

 through the tail of the comet;, one ascent should also 

 precede, and one should follow, the principal ascent by 

 preciselv similar intervals of time. 



Messrs. Assmann and Teisserenc de Bort suggest that it 

 might be possible to carry out ascents of manned balloons 

 as well as of ballons-sondes, and it is suggested that the 

 aero clubs of different countries should cooperate in the 

 observations. A letter has also been sent out by M. 

 Teisserenc de Bort describing the apparatus he has designed 

 and used for several vears for collecting samples of air 

 from great heights. The use of Aitken 's dust counter is 

 recommended in connection with the ascents of manned 

 balloons, and similar observations should be made at the 

 earth's surface. Though it is unlikely that the passage of 

 the earth through the tail of a comet will cause any 

 measurable change of temperature in the upper air, yet it 

 is felt bv those engaged in the investigation of this subject 

 that such a rare occurrence should not be allowed to pass 

 without some notice. 



Meteors from Halley's Comet. 



Mr. Denning writes : — 



" During the first week in May the weather was unsettled 

 and stormv, and Halley's comet could not be well observed, 

 nor could' its supposed meteoric shower from Aquarius 

 be suitably watched. Several meteors were seen, how- 

 ever, at p'laces where the sky was clear or partially so, 

 and they were directed from the radiant point of the comet, 

 though 'no brilliant -display of these phenomena seems to 

 have been witnessed in England. 



" There is a probability of an abundant display of 

 meteors on the morning of May 19, when the earth may 

 encounter the comet's tail, but this is doubtful. The sky 

 should be carefully watched, however, on the morning 

 named with the view of observing any meteors or pecuhar 

 auroral effects that may be visible. 



" A rich display of meteors is reported to have been 

 witnessed at Cape Town on the morning of May 7 between 

 2 and 5 a.m. There was no very active shower seen in 

 England on the date mentioned, and further particulars 

 will be awaited with interest. 



" A fireball, presumably connected with Halley's comet, 

 was noticed at Guernsey and other places on the morning 

 of May 3 at about 2.50 a.m. As viewed from the Channel 

 Island's, it had a long path ascending from just under 

 j8 Pegasi to under j3 Cassiopeise, with a duration of four* 

 seconds. 



"The real path of the meteor was from sixty-seven t( 

 fortv-six miles in height, and its position over the EnglisI 

 Channel from near Dieppe to south-west of the Isle oi 

 Wight, and its course, of some 137 miles, was traversed 

 at a velocity of about thirty-four miles per second. Thij 

 is a slower rate of speed than calculation implies to the 

 Aquarids, but atmospheric resistance evidently moderated 

 the meteor's native velocity. From the south coast_ ol 

 England— especially Sussex' and Hampshire— the object 

 must have been a splendidly luminous one, presenting a 

 very long and graceful flight along the southern sky, but 

 I have not hitherto received any observations from this 

 particular part of the country. 



