640 



NA TURE 



[October 26, 1905 



sented by M.M. M. Stefanik, G. Millochau, and J. J. 

 Landerer, who were in charge of the several instruments. 



The results, which are of only a preliminary nature, are 

 too numerous to give in detail here, but all the observ- 

 ations, both visual and photographic, appear to have been 

 successful. 



.\I. E. Stephan, of the Marseilles Observatory, was placed 

 in charge of one of the expeditions organised by the Bureau 

 des Longitudes, and, accompanied by M. Borrelly, occupied 

 the same station as Mr. Newall, at Guelma (Algeria). 



The equipment of this expedition consisted of a telescope 

 ol 40 cm. aperture and an equatorial of 95 cm. aperture 

 and igo cm. focal length. A number of visual observations 

 of the corona, the prominences, &c., were successfully 

 made. 



Nova Aquil.e No. 2. — Circular No. lob of the Harvard 

 College Observatory describes the discovery and subsequent 

 observations of Nova Aquihu No. 2. The Nova was dis- 

 covered on a plate taken with the ii-inch Draper telescope 

 on .\ugust 18 for the Henry Draper memorial series. The 

 spectrum, although faint, showed the lines H5, H7, 4272, 

 4646, and H;8 very broad and bright, H7 and H/3 having 

 accompanying dark lines on their more refrangible edges. 

 The helium line 4646 is slightly stronger than 4272, and 

 the whole spectrum closely resembles that of Nova 

 Persei No. 2, as photographed on March 30, 1901. 



Some two or three hundred plates of this region are 

 included in the Harvard series, and twenty-nine of them, 

 taken before .\ugust 18, have been examined, but no trace 

 of the Nova before that date has been discovered. 



Two photographs showing the region half a degree 

 square around the Nova, taken on August 15, 1903, and 

 August 31, 1905, respectively, are reproduced in the 

 Circular, and on comparing them it is at once seen that 

 the Nova does not appear on the former, although it is 

 quite a conspicuous object on the latter plate ; stars of 

 magnitude 15-7 are shown on the earlier plate. 



Prof. Pickering's tabulated statement of the observed 

 magnitudes of the Nova from August 31 to September 22 

 shows that this object gradually decreased in brightness 

 from magnitude 10-41 on the first named date to magni- 

 tude 11.23 on the second. When first photographed the 

 Nova's magnitude was about 7.0. 



It follows from the Harvard observations that the Nova 

 first appeared between August 10 and August 18, but it 

 is hoped that, when the plates taken at ,'\requipa' during 

 that period arrive at Cambridge (Mass.), this interval may 

 be greatly reduced. 



Star with a Large Proper Motion. — The method 

 employed at Harvard College Observatorv for the detection 

 of variable stars, viz. the superposition 'of a photographic 

 plate upon a glass positive of the same region, photo- 

 graphed on an earlier date, has led to the discovery that 

 the star A.G.C. 6886 has a large proper motion. Whilst 

 thus examining two plates of the Large Magellanic Cloud 

 taken on April n, 1898, and December 5, 1904, respectively' 

 Miss Leavitt found that this star had moved appreciab'lv 

 during the interval, and a comparison of the positions given 

 in several of the older catalogues compiled since 1821; 

 confirmed the fact. 



The discussion of the data obtained from the comparison 

 showed that the annual proper motion in V...\. is -0066s. 

 in declination -(-i".i4, and along a great circle i".28 ' 



The total number of stars shown on the original 

 negatives is about 300,000, and it is probable that none of 

 these except A.G.C. 6886, has an annual proper motion 

 exceeding three-quarters of a second (Harvard College 

 Observatory Circular, No. 105). " 



Observations of Perseids, August.— The detailed 

 results of the Perseid observations, made at the meteor- 

 ological observatory at Pavia on August 8, 9 10 and ii 

 are given in No. 8, vol. xxxiv., of the Memorie dell'a 

 !>octetd dcgh Speltroscopisti Italian:. 



On the night of August 8-q seven observers recorded ici 

 meteors, and determined the trajectories of 23 of them 

 J he maximum horary rate occurred between oh. and ih" 

 (August 9). during which time 53 meteors were seen. On 

 the succeeding night the watch lasted from 22h. to 3h -m 



and the same number of observers saw 252 meteors, of 

 which they recorded the paths of 28. The maximum rate 

 occurred during the last hour, when 93 meteors were seen. 

 The third night produced 264 meteors, and of these the 

 seven observers recorded the trajectories of 18 during their 

 watch of 4h. 56m. The maximum horary rate of the 

 whole shower, as observed at Pavia, was recorded during 

 this watch, when 100 meteors were seen between 2h. and 

 3h. on the morning of August 11. 



Of the 669 meteors seen during the three nights, 27 were 

 recorded as being brighter than, and 139 as being equal to, 

 the first magnitude, whilst " swift " and " white " were 

 the descriptive terms applied to the majority of them. 



MATHEMATICAL AND PHYSICAL SCIENCE 

 AT THE BRITISH ASSOCIATION. 



T^HE great number of astronomers present during the 

 South African meeting caused astronomy to play a 

 larger part in the proceedings of the section than it has 

 done in recent years, and many of the most important 

 communications and discussions were on astronomical sub- 

 jects. The number of papers on pure mathematics and 

 on physics was relatively small. 



Of the mathematical papers, one by Prof. Harzer on 

 ancient Japanese mathematics was of special interest. 

 Prof. Harzer finds on examining ancient Japanese records 

 and works that several of the theorems discovered in 

 Europe during the seventeenth century were known at least 

 as early to Japanese mathematicians. As an example, the 

 expansion 



I I 2-4-6- • ■ 2B 2^4.2 

 «0+I ■ 1.3.5. . . (2|8 + 1) 



(arc sin _)')- = 



NO. 1878, VOL 72] 



due to Kowa Seki (1642-1708) may be quoted. 



Mr. M. Cashmore showed how chess magic squares, i.e. 

 squares of numbers which add up to the same amount 

 along every path across the square in the direction of a 

 rook's, a bishop's, or a knight's move, can be constructed 

 by superposing on each other two types of subsidiary 

 squares, which can be formed by simple rules. 



Prof. Perry gave an account of the approximate method 

 he had used to determine the stresses which occur in a 

 winding rope carrying a cage when the upper end of the 

 rope is suddenly stopped. 



Mr. H. G. Fourcade described his instrument for stereo- 

 scopic surveying. It consists of a photographic camera 

 which may be fixed in turn at the two ends of a base line 

 with its axis perpendicular to that line. In front of, and 

 close to, the sensitive plate a reseau scale on a glass plate 

 is placed, and is reproduced on the two photographs taken. 



The two are examined together in a measuring machine 

 similar to that used in stellar photography, and by means 

 of micrometer screws any portion of the picture may be 

 made to appear in relief and coincident with an index. 

 The distance of that portion from the base line may then 

 be determined from the micrometer readings. Each deter- 

 mination takes about two minutes, and with a base of 

 300 metres the probable error does not exceed i part in 

 1000 for a distance of 10,000 metres, and is less for 

 shorter distances. 



Prof. Perry raised the question of the teaching of 

 elementary mechanics, and pointed out that the average 

 boy who enters a technical college is so badlv educated 

 that his first year has to be " wasted in the study of 

 school subjects." Then three years are found to be in- 

 sufficient to teach him "everything an engineer is likely 

 to want in his profession," which many colleges foolishlv 

 attempt to do, and a fourth or even a fifth year is added. 

 He urged that in teaching science to boys from nine to 

 thirteen the methods of .Mr. Barlow, of " Sandford and 

 Merton " fame, should be followed, until they know some- 

 thing of levers, weighing and measuring, specific gravities, 

 barometers and thermometers, and of electricity and 

 magnetism. At the age of fourteen a bov should' know 

 elementary algebra and trigonometry, sho'uld be able to 

 differentiate and integrate, and apply the calculus. The 

 principles that if forces are in equilibrium their vector sum 

 IS zero, and the sum of their moments about any axis is 



