624 



NA TURE 



[October 25, 1894 



from Elkin's new computed values of Bessel's measures made 

 with the Konigsberg heliometer. The following table is of 

 interest, as it brings out the great accuracy of the Gbitingen 

 observations, and leads to suggestions regarding the grouping 

 of the stars in numerous systems. 



Stan. 



k 



I 



d 

 12 



1\ 

 28 



s 



f 



h 



34 

 40 



Gsttingen.— Konigsberg 



Relative proper motion for 50 

 years in 



Ktcl- 



+0 06 

 + 0'20 

 -066 



tO-49 



•r052 

 ^001 

 + 009 



-060 



+ 0-I2 

 + 1-30 

 -0-04 



-f0'04 

 -f 060 

 + 0-44 



Magnitude. 



o 13 

 046 

 063 

 047 

 0-49 

 014 

 018 

 0'33 

 0-55 



25 



1 42 

 017 

 0-05 



Direction. 



060 

 o'64 



29 o 

 23 -2 

 2533 

 75'' 

 811 



4"4 

 266 



259-5 

 268-9 



266 

 122-5 

 194-I 

 53' 

 67-3 

 3S7 



Dr. Ambronn points out that the proper motions appear to 

 show, just as those of Elkin's indicated, that the stars form not 

 one but several systems. As will be seen from the table, g, l>, 

 i; /(and 28) appear to group themselves together, so also f with 

 «", and the three stars /«, d, 12, with one another. Kor a more 

 definite opinion on this point it is suggested that the number of 

 stars observed must be greatly increased. 



The result of the triangulation shows, however, that by a 

 suitable determination of the instrumental constants and due 

 care in arranging the measures for reduction, small helio- 

 meters can give results, especially with regard to distances, 

 which compare very favourably with instiumenis of much larger 

 size. 



The Fifth Satellite of Jupiter. — A series of micro- 

 metrical measures of the fifth satellite of Jupiter, made during 

 the opposition of the planet in 1893, is contributed to the 

 Aslrotiomical Journal, No. 325, by Prof. E. E. Barnard. 

 From numerous observations. Prof. Barnard is confident that 

 the satellite is not brighter than the ihirteenih magnitude. 

 Its sidereal period appears to be llh. 57m. 22-6i8s. Filar- 

 micrometer measures of the diameters of Jupiter were m.ade in 

 the course of the work, the following values being obtained : — 



Equatorial diameter 90, 190 ± 56 miles. 



Polar diameter 84,570 ± 75 miles. 



The polar compression oblained from these measures is 1/15 98. 

 The mean of measures of east elongations of the satellite, made 

 from September 1893 to January 1894, correspond to a dis- 

 tance of 111,910 miles. But on account of the eccentricity and 

 revolution of the orbit of the satellite, the elongation distance is 

 a varying quantity. M. Tisserand was led to conclude, a short 

 time ago, that the major axis of the satellite's orbit must make a 

 complete revolution in about five months, lie returns to the 

 subject in ComplnrcnJui for October S, having used Prof. 

 Barnard's new measures to make another determination of the 

 eccentricity and the longitude of perijove at a given epoch. 

 Mis discussion of the observations has led to the following 

 re.sults : — Semi-major axis, 47' -906 ; eccentricity, 00073; 

 longitude of perijove at the epoch October 28, 1892, - 14". 



A' 



THE PAST SUMMER. 



N examination of the meteorological results for the six 

 months from April to September exhibit some features 

 of interest by way of showing how the several elements of 

 temperature, rainfall, and sunshine combine to make up what 

 is commonly called weather, and how, as in the case of the 

 summer in question, the absence of sunshine can mar the 



NO. 1304, VOL. 50] 



season. In some summers the character of the weather varies 

 considerably in different parts of the kingdom, but during the 

 recent summer there w.is a great similarity in the conditions 

 over the whole of the British Islands, and consequently the 

 principal facts in the following summary, deduced from observa- 

 tions in the neighbourhood of London, will, to a great extent, 

 be an index for other parts of the kingdom. 



Table showing the Temperatures at Greenwich for the several 

 Months and for the whole Summer. 



S 



V 



s 



.\pril ... 

 May ... 

 lure .. 

 July ... 

 August. 

 Sept. ... 



S>-9 

 Sr8 

 59-8 

 636 

 61-4 

 55-2 



E . 

 o V 



!5> 



■^3-8 



-2'I 



-0-6 

 o o 



-«s 



-3'o 



S 2 



61-8 

 6i-i 

 69-2 

 73 o 

 69-2 

 62-2 



Summer | 57-3 



-06 66"i 



-1-4-6 

 -3' 

 -17 

 - ro 

 -3-6 

 -S'« 



23 s 



Sol 



41 9 



42-5 

 50-4 



541 

 536 

 48-1 



-1-6 1 48-4 



o-g 



4 

 21 



•9 

 18 



26 

 24 



The averages used in the above comparison are for the 50 

 years 1 84 1 to 1890. A warm day is one on which the mean 

 daily temperature is above the average, and a cold day is one 

 on which the mean daily temperature is below the average. 



It will be noticed that the mean maximum temperature is 

 below the average, except in April ; while the mean minimum 

 temperature is in excess of the average, except in .May and 

 September. The highest day temperatures at Greenwich only 

 reached 70° or above on 51 days, and they were distributed as fol- 

 lows throughout the summer : — April, 3 days; .May, 2 ; June, 12 ; 

 July, 21 ; August, 12; and September, I. There were in all 

 only 7 days with a tem]ieratuie of So° or above ; they occurred as 

 follows : — June, 3 ; July, 3 ; and August i. For the last 50 years, 

 1S45 1S94, there have been on the aver.age 75 da\s with a tem- 

 perature of 70^ and above, and 15 days with a temperature of 

 80' and above. The summers of i860, 1S79, and 1SS8 each 

 had a fewer number of hot days than the summer which has just 

 passed, while 1S46, 1857, 1S58, 1S65, 1S6S, and 1893 each had 

 double the number of hot days. L:tst year the mean tempera- 

 ture for the whole summer «as more than 3' in excess of the 

 mean for the summer this year, but the summer last year was 

 warmer than any during the last halfcenlury, although it was 

 only o°*2 warmer than in 1868. 



The following table gives the rainfall and sunshine at Green- 

 wich, and the sunshine values at Westminster, for the several 

 months and for the whole summer : — 



The above figures show that rain fell with great frequency, 

 but the amount was by no means excessive, and, with the 

 exception of July and August, the monthly falls were below 

 the average. A slightly different result is obtained if the com- 

 parison is made with the last 50 years, 1845 to 1894, the 

 avcr.igc total fall in summer for that period being 12 '66 inches, 

 which gives a deficiency of 008 inch only for the recent 



