December 29, 1904] 



NA TURE 



OUR ASTRONOMICAL COLUMN. 

 Astronomical Occurrences in January, 1905. 

 Jan. 2-3. Epoch of January meteors (Radiant 230° + 53°). 



6. 4h. 52m. to 7h. 5m. Transit of Tupiter's Sat. III. 

 (Ganymede). 



8. 2h. Saturn in conjunction with Moon (Saturn 



3°3'S.). . ^ 



9. 3h. Venus in conjunction with Moon (Venus 2 13 



S.). 

 ,, II h. Juno in conjunction with Moon (Juno 0° 11' S.). 



10. 5h. 9m. to 6h. 23m. Moon occults (p Aquarii 



(Mag. 4-4). 



11. Perihelion Passage of Encke's Comet. 



13. 8h. 52m, to iih. 6m. Transit of Jupiter's Sat. III. 

 (Ganymede). 

 ,, loh. 36m. Minimum of Algol (/3 Persei). 



15. Venus. Illuniinated portion of disc = o'650, of 



Mars = 0^903. 



16. 7h. 25m. Mmimum of Algol (S Persei). 



24. I2h. 43m. to I3h. 40m. Moon occults $ Virginis 

 (Mag. 3-8). 



27. loh. Mars in conjunction with Moon (Mars 2° 45' 



S.). 



28. I5h. 7m. to i6h. Ilm. Moon occults 7 Libr« 



(Mag. 4-1). 

 Ele.ments and Ephemeris of Comet 1904 d. — Circular 

 No. 69 from the Kiel Centralstelle contains a set of elements, 

 •calculated by Herr M. Ebell from the observations made on 

 December 17, 18, 19, and a short ephemeris, for comet 

 1904 d, recently discovered by M. Giarobini at Nice. They 

 .sire as follows : — 



Elements. 



T = 1905 Jan. 3 '2814 Berlin. 

 «== 75' 9' 'SI 

 S = 225° i'-2 V 1904-0 

 i = 103° 27' -3 J 

 log? =0-27173 



Ephemer 



I2h. {M.T. Berlin). 



S log A 



Bright- 



Jan. 



.. 16 37 56 ... +31 45 ... 0-3328 ... 112 

 .. 16 49 48 ... +33 S3 ... 0-3234 ... 117 



17 2 37 ... +36 8 ... 0-3146 ... 1-22 



Brightness at time of discovery = 10. 



from the above it will be seen that both the northern 

 ■declination and the brightness of the comet are increasing, 

 but at the same time its right ascension is approximating 

 more closely to that of the sun, thereby rendering observ- 

 ations increasingly difficult, and only possible during the 

 few minutes preceding dawn. 



Oi!SKRV.\Tioxs OF BRIGHT Meteors. — During a sea 

 voyage undertaken in 1903-4, Dr. J. Moller, of Elsfleth, 

 observed a large number of meteors, and in No. 3984 of 

 ^:he .Istronomische Nachrichten he records the essential data 

 regarding the observations of the sixteen brightest objects 

 seen during November-December, 1903, and March, 1904. 

 Of these, two were as bright as Jupiter, and five were 

 brighter than Saturn. The latitude and longitude of the 

 place of observation are given in each case, so that in the 

 event of duplicate observations having been made the real 

 paths may be computed. 



The same observer recorded in No. 3071 of the same 

 journal an authenticated naked-eye observation of Jupiter's 

 third satellite on November 1, 1903. 



Tm; Gre.1t Red Spot ox Jupiter. — In a note to No. 3983 

 of the .\stronomische Nachrichten Mr. Denning gives the 

 results of his own and the Rev. T. E. Phillips's observations 

 of the Great Red Spot since the last conjunction of Jupiter. 

 They show that for the seven months prior to last .September 

 ■the motion of the spot indicated a rotation period, for the 

 zone wherein it is located, of 9h. 5501. 38-6s., a shorter 

 period than any observed since 1883, when it was 

 9h. 55m. 38-2S. 



In the same publication Mr. Stanley Williams gives the 

 result^ of his observations of this phenomenon, and shows 

 that from his eye-estimates of the times of transit, during 



XO. '835, VOL l] 



the period August, 1903, to January, 1904, the average time 

 of rotation was 9h. 55m. 41.52s. 



He points out that this is a remarkable increase on the 

 rotation period (viz. 9h. 55m. 39.66s.) of the preceding 



Report of the United St.ites Nav.\l Observatory. — 

 Rear-.\dmiral Chester's report of the work done at the 

 United States Naval Observatory during the fiscal year end- 

 ing June 30, 1904, shows that the observatory and the staff 

 are still maintaining their reputation as regards the number 

 and e.xcellence of the observations made. In all 15,287 

 observations were made, including photographs of the sun 

 taken on 210 days which show an increase of 93 davs on 

 which spots and facul;e were recorded on the solar disc. 

 .\ new photo-visual triple objective with an aperture of 

 75 inch and a focal length of 65 feet, giving a 7-inch 

 image, is to be obtained for the photoheliograph, and will 

 also be used on future eclipse expeditions for photographing 

 the corona. In regard to next year's eclipse the superin- 

 tendent asks for a special grant of 1200/. and re- 

 commends the employment of a man-of-war and its crew- to 

 assist in the observations, which he suggests should be 

 made at two widely separated stations in Spain. 



The report also contains individual reports from the 

 assistant in charge of each department, and records the 

 personnel, the routine work performed with each instru- 

 ment, and the publications issued during the period with 

 which it deals. 



The branch observatory at Tutuila, Samoa, has now been 

 established, and placed under the supervision of assistants 

 from Washington. 



MATHEMATICAL DRAWING.' 

 T^HE appearance of a useful little book by Prof. Gibson 

 may be made the occasion of emphasising the import- 

 ance of drawing in mathematics, whether pure or applied, 

 especially as the University of London has recently made a 

 paper on drawing compulsory for all mathematical candi- 

 dates for the B.Sc. degree. It was not without due con- 

 sideration of the attendant difficulties that this step was 

 taken. For the last two years the paper on drawing 

 was left optional for the candidates in order that teachers 

 as well as students should have time to obtain some definite 

 notion of what is required ; but even now, in the absence 

 of well established text-books, a considerable amount of 

 uncertainty exists as to the nature and scope of the subject. 

 Time will, no doubt, set this right, and we welcome Prof. 

 Gibson's text-book as assisting towards the desired object. 



There are three prominent conceptions of mathematical 

 drawing which may be noticed. These are: — (i) plotting, 

 which means the construction of curves by taking a set of 

 successive values of an abscissa and from them calculating 

 (by a book of tables or otherwise) the values of the corre- 

 sponding ordinate, and finally marking the positions of the 

 points on squared paper ; (2) the construction of curves — 

 usually conic sections — from certain geometrical data ; 

 (3) what is generally called " geometrical drawing," 

 embodying the principles and processes of projective 

 geometry, and including problems in three dimensions. 

 This is, perhaps, a rough division, but it w-ill suffice. 



Plotting may be a very humble process — " mere " plotting, 

 as it is sometimes contemptuously called — or it may be what 

 has long been known as curve tracing, and is to be found 

 in treatises on the differential calculus. But even in this 

 latter and higher character it is not (at least as usually 

 employed by students) a system of accurate drawing. The 

 construction of circles, and conies generally, from assigned 

 data is certainlv not a pure exercise in drawing, because it 

 involves a very large knowledge of theorems on the part 

 of the student. .An exercise in this subject is apt to be, in 

 reality, a severe examination in Euclid or in the theory of 

 conic sections, and it cannot be what was intended by the 

 advocates of a paper on drawing. With regard to projective 

 geometry the case is somewhat different ; the principles in- 

 volved are not very numerous, and it cannot be said that a 



1 " An Elementary Treatise on Graphs." By George A. Gibson, M.A.. 

 F.RS.E., Professor of Mathematics in the Glaseow and West of .Scotland 

 Technical College. Pp. x -|- 183. (London : Macmillan and Co., Ltd.) 



