December 18, 1902] 



NA TURE 



■59 



nine new minor planets. Three of these were found on a plate 

 taken by Prof. Wolf on November 20, three others on a plate 

 taken by Mr. Dugan on November 21, and the remaining 

 three were found on a plate secured by Prof. Wolf on 

 November 21. 



Elements and Ephemeris of Comet 1902 d. — M. G. 

 Fayet, of the Paris Observatory, has computed the following 

 elements and ephemeris for the orbit of the new comet, from 

 observations made on December 3, 5 and 8 : — 



T = 1903 March 13-976 M.T. Paris. 



Tt = 119 52 401 



a = 117 39 21 1 



i = 43 53 9 1 

 log a = 0-45401 J 



1902 



Ephemeris 12/1. M. T. Paris. 



Brightness at time of discovery 



log a Brightness. 



II 

 I 2 

 I 2 



1 "3 

 1 '3 

 1'4 



An observation was made on December iod. I3h. 37m. o at 

 Heidelberg by M. Courvoisier, and gave the following position 

 for the comet: — 108° 47' 12",- o° 48' 15", and this gives a 

 correction to Fayet's ephemeris of - 2s. and +o'-6 (Kiel 

 Circular, No. 55). 



" Companion to 'The Observatory,' 1903." — This annual 

 collection of elements and ephemerides, just published, contains 

 its usual excellent list of tables and information in regard to the 

 astronomical phenomena which will take place during the coming 

 year. 



The information concerning the various meteor showers and 

 double stars is supplied by Messrs. Denning and Maw respect- 

 ively, and M. Loewyhas again contributed advance proofs from 

 which the variable-star ephemerides have heen compiled. 

 The latter show a considerable increase in number this year. 



JUPITER AND HIS GREAT RED SPOT. 



""FHOUGH Jupiter has been unfavourably placed for European 

 -*- observers during the present year, his surface markings have 

 been extremely interesting, of great variety and in plentiful 

 numbers. The English climate, even at its best, can scarcely 

 be said to suit astronomical work in an eminent degree, but its 

 characteristics in 1902 have proved unusually bad, in fact, 

 atmospheric conditions have combined with the low position 

 of the planet to render observations difficult, and they have 

 generally had to be pursued with definition of very inferior 

 quality. The seeing has been recorded as " very good " on six 

 nights only out of seventy-five, and in 1901 the result was 

 equally disappointing, for the image was really sharp and satis- 

 factory on five nights only out of seventy-one ; but in 1901 the 

 planet was about 5 lower (Dec. 23^ S.) than in 1902 (Dec. 

 18° S.), and though the difference is not great, it ought to have 

 operated strongly in favour of the present year had other 

 circumstances been equal. 



The most noteworthy incident in connection with recent 

 studies of Jupiter is to be found in a very pronounced acceler- 

 ation of motion in the great red spot. This first made itself 

 evident in 1901, but it has been intensified during the past 

 summer. For about twenty-three years, uninterruptedly, this 

 singular marking had exhibited a constantly increasing retard- 

 ation, which caused its rotation period to lengthen from about 

 9h. 55m. 34s. to nearly 9h. 55m. 42s. But in 1901 it declined 

 to 9h. 55 m - 4's., and during the present year the rate has been 

 about 9h. 55 m - 39-j s ' And this increase of velocity has been 

 contemporary with the outbreak of a large, irregular or multiple 

 marking of a dusky hue, in the same latitude of the planet. 

 This new object, apparently first seen in May, 1901, has shown 

 a rotation period of 9I1. 55m. 18s. , which corresponds with that 

 nf the south temperate current. It seems a probable conjecture 

 thai the presence of the marking just referred to may have forced 

 the red spot along at a more rapid rate than that which it 



NO. 1729, VOL. 67] 



exhibited in previous years. In June, July and August of the 

 present year, the red spot was almost surrounded by the material 

 of the new marking, and the quicker motion of the latter may 

 well have accelerated the movement of the former. But no 

 certain conclusion can be arrived at, though the facts are signifi- 

 cant and suggestive. Possibly the phenomena alluded to may have 

 been practically coincident in date, but devoid of any physical 

 relationship. And in this connection it will be useful to 

 remember that the red spot has always been situated in a 

 stream flowing along with much greater celerity than the rate of 

 its own motion. 



In September, the material of the new marking had passed to 

 the preceding (W.)side of the red spot, and hence it was 

 expected that the accelerated motion of the latter would cease, 

 but the differences in motion have been comparatively slight, so 

 that errors of observation make it unsafe to form definite con- 

 clusions. It will be advisable when the planet disappears from the 

 evening sky in January next to collect all the transit times of the 

 red spot' recorded during the present apparition, as it may then be 

 possible to determine with accuracy the extent of the acceleration 

 and the variation in its rate, if any, during the summer and 

 autumn. If a large number of observations are forthcoming, it 

 will be desirable to group them into monthly or bi-monthly 

 periods and ascertain the mean longitude of the spot for each of 

 these, when the rate of its drift will be seen and the errors of 

 individual transits practically obliterated. 



At Bristol, the following estimated transits have been obtained 

 with a 10 inch reflector and a power of 312 : — 



Date. G.M.T. Lonfitude. 



1902. h. m. 



April 28 16 14 45-9 



May 20 14 23 44-7 



. ... 44-8 

 422 

 45-i 

 43'9 

 44'S 

 40-2 



4i-7 

 42-5 

 41 "7 

 396 

 38-0 

 40-3 

 40-5 

 379 

 37'9 



40'2 



37-1 

 37 - i 

 36-9 



39'4 

 . ... 36-1 



39-1 



During the present year, a number of white and dark spots have 

 been visible on the north side of the north equatorial belt, and 

 the mean rotation period of these has been about ten seconds less 

 than that shown by the red spot. A new belt has lately formed 

 on the northern side of the spots alluded to. The equatorial 

 current of the planet has been moving, as nearly as possible, at 

 the same rate as during 1901, for the mean rotation of twenty-four 

 spots is about 9h. 50m. 29s. There has been an abundance of 

 slow-moving N. and N.N. temperate markings, but these have 

 seldom been well seen owing to the confused definition. 



W. F. Denning. 



SOME LIMITS IN HEAVY ELECTRICAL 

 ENGINEERING. 1 



TT is customary for a presidential address to be a review of 

 •^ the development of the science with which the Institution 

 is particularly concerned. Such a review is especially bene- 

 ficial in the case of such a rapidly growing industry as electrical 

 engineering, as the outlook changes considerably during a yeir. 

 Instead of a review of the past, a dream of the future may 

 take the form of, a 'presidential address. This form has great 



1 Abridged from the inaugural address by the president of the Institu- 

 tion of Electrical Engineers, Mr. James Swinburne. 



