August 2, 1877] 



NA TURE 



267 



hill in 1876, and by himself in 1877. Sir W. Herschel's 

 measures may be set aside at once as not sufficiently exact 

 for a discussion of a moderate proper motion ; his angle 

 in 1 78 1 is the result of a single measure, and his dis- 

 tances, as is well known, are in defect, when they exceed 

 a minute. Taking then Struve's epoch, 1836-06, as the 

 earliest reliable datum we possess, and bringing it up to 

 Dembowski's epoch, 1863-37, with Leverrier's proper 

 motion for Aldebaran, we find no greater difference than 

 may be accounted for by unavoidable error of observation, 

 so that Struve's inference on comparing the Pulkowa 

 measures, in 1851 with the Dorpat measures of 1836, 

 " itaque comes motus non est particeps, sed in coelo 

 quiesca videtur," and Dembowski's conclusion when 

 speaking of this object and of X Auriga," " Les dif- 

 ferences s'accordent assez bien avec les mouvements 

 propres des deux principales," are thus supported. The 

 angle, however, should now be less than is assigned 

 by Mr. Gledhill and M. Flammarion from their own 

 measures (35°-5), and further careful measures will be 

 desirable to clear up a possible question of personal 

 equation. If we reduce Struve's angle for 1836 with 

 Leverrier's proper motion of Aldebaran to the present 

 year, we find an angle nearer 32°-5 than 35°'5. 



The Third Comet of 1759. — This comet was not 

 observed until January, 1760, but appears in our catalogues 

 as comet 1759 III., from the circumstance of the perihelion 

 passage ha\-ing occurred in December of that year. It 

 approached very near the earth, but was not a conspicuous 

 object more than a few days. There are several references 

 to the comet in the Annual Register for 1760, where we 

 learn that it was " discovered and astronomically observed 

 by Mr. Dunn at his Academy at Chelsea," who had 

 determined the positions of Halley's comet on every 

 evening during the first week of May previous. Pingrd 

 states that the sky, having been constantly overcast at 

 Paris for several days, all the astronomers of that capital, 

 including Cassini de Thury, Maraldi, Lacaille, and Messier, 

 detected the comet on the evening of January 8 ; Dunn is 

 credited with having found it on January i. It was seen 

 at Lisbon on January 7. For the purpose of these 

 remarks we shall adopt the elements of Lacaille, in 

 deducing the apparent places of the comet. 



There is no reason why the comet should not have 

 been found on January i, if atmospherical conditions had 

 been favourable, but it must have been on the morning, 

 not on the evening of that day. In fact, the comet would 

 rise soon after 1 o'clock a.m., in London, and would be 

 upon the meridian a few minutes before six at an altitude 

 of more than 23°. It is, however, distinctly stated in the 

 Annual Register that Dunn discovered the comet in the 

 evening, that " it appeared to the naked eye like Jupiter 

 or Venus through a thick fog, and made a near appulse 

 to the star in Orion's right knee, and moved more than 

 four degrees of the heavens in four hours of time." This 

 can only refer to the evening of January 8. The elements 

 give the following positions : — 



d. h. 



January 8 8 



8 12 



earth. 

 0-0734 

 0-0760 



88 59 ... 99 55 



84 17 ... 98 34 

 There was, therefore a motion of upwards of four degrees 

 in as many hours, and soon after midnight the comet 

 would not be more than i:f° from Orion's right knee, or 

 K Orionis. It is therefore pretty certain that Dunn did 

 not precede other observers by a week, as might at first 

 sight appear from the statement in the Register. Clouded 

 skies had evidently prevailed in Western Europe for 

 some days, and the comet was detected on the same 

 evening, January 8, on the heavens clearing, in England, 

 France, and Holland. 



The rapid course of this retrograde comet will be 

 apparent from the foUovnng positions, calculated for 

 Greenwich midnight. 



R.A. 



N.P.D. 



Distance. 



Jan. 5 ... 165 36 



„ 6 ... 147 II 



„ i7 ... n6 27 



,, 8 ... 84 17 



„ 9 ... 64 9 



„ 13 ... 39 22 



109 22 ... 0112 



iio 3 ... 0-083 



106 58 ... 0068 



98 34 ... 0-076 



91 30 ... OIOI 



82 33 ... 0-24S 



Between January 7 and 8 the comet passed over 32^° in 

 arc of great circle, and was nearest to the earth soon after 

 midnight on the former date. On January 9 in the 

 evening Dunn says the comet passed near ^ and v in 

 Eridanus, and we find from Lacaille's elements that at 

 5h. 39m. P.M. it would have the same right ascension as ^, 

 with only 40' greater decimation. So far as regards 

 position the comet might have been observed as early as 

 the day of perihelion passage, December 16, when it was 

 in R.A. 199° and N.P.D. 103°, rising in London at 

 2h. 45m. A.M. ; but the intensity of light was only -prjth 

 of that on the evening of January 8, when it was generally 

 discovered. It is rather unfortunate that it was not 

 observed over a longer period, since it appears certain 

 that in its approach to perihelion it must have passed 

 very near to the planet Jupiter, and we might expect a 

 sensible deviation from the parabola. On November 7, 

 1758, Lacaille's orbit would give the comet's distance from 

 Jupiter less than 0-05 . 



METEOROLOGICAL NOTES 

 Sun-spots and Rainfall of Calcutta. — Mr. E. 

 Douglas Archibald, of Naini Tal, has written an in- 

 teresting letter to The Englishman, the leading Calcutta 

 newspaper, in which he shows from the observations 

 made from 1837 to 1876, that the winter rainfall (Nov. 

 to April inclusive) of Calcutta is marked by a distinct 

 periodicity, the maximum rainfall occurring during the 

 years of minimum sunspots, and the minimum rainfall 

 during the years of maximum sun-spots. The following 

 are the figures for the years of the sun- spot cycle begin- 

 ning with the year of minimum sun-spots : — 



Average Rainfall. 



1st and 2nd year of cycle ... 6'44 inches 



3rd and 4th „ ■•• 5'93 „ 



5th and 6th „ ... 4-44 „ 



7th and 8th „ ... 5-03 „ 



9th and loth „ ... 6-15 „ 



ilth „ ... 8-49 „ 



the average rainfall for the forty years being 5-41 inches. 

 Mr. Archibald is of opinion that this peculiarity, which 

 is the reverse of what obtains as regards the rainfall of 

 the whole year, in its relation to sunspots, will be 

 found not to occur much farther south than Calcutta, 

 and that it will be more decidedly marked over the 

 region farther to the north lying more immediately under 

 the great range of the Himalayas. The point is one of 

 very considerable interest and deserves the fullest inves- 

 tigation, since, if the supposition proves to be correct, it 

 will doubtless lead to a more exact method of examining 

 the rainfall in its relation to sun-spots. It may be 

 remarked that the winter rainfall at Sydney (in the 

 southern hemisphere) from 1840 to 1876, which is situated 

 within the latitudes indicated by Mr. Archibald, exhibit? 

 the same peculiarity as that of Calcutta in its relation to 

 the sun-spot period. 



Winds of the South Atlantic— M. Brault an- 

 nounces the pubhcation by the French Marine of a series 

 of new meteorological charts giving the direction and force 

 of the winds of the South Atlantic for each of the four 

 seasons, the charts being similar to those published by 

 M. Brault about two years ago on the winds of the North 

 Atlantic. The new charts contain the results of 189,573 

 observations of the wind. The general movement of the 

 winds in summer over this portion of the globe resembles 



