456 report — 1884. 



the country. We shall therefore only give a short summary of the results 

 which have been obtained. In 1878, Mr. Fred. Chambers ' pointed out that 

 between the years 1848 and 187G the curve of mean pressure both in 

 summer and in winter showed a similarity to the sunspot curve. The 

 greatest barometric pressure occurs a short time after the minimum of 

 sunspots. Allan Broun 2 showed that the results for the Bombay observa- 

 tory are confirmed by the records of other Indian observatories. Mr. Archi- 

 bald, 3 soon afterwards gave evidence of a periodical variation of 

 atmospheric pressure at St. Petersburg, where, however, the maximum 

 pressure occurred two years after the sunspot maximum. The matter 

 was fully entered into by Mr. Blanford, 4 who has confirmed the previous 

 results. At the Indian stations, especially at those situated near the 

 equator, the maximum of atmospheric pressure seems to occur at or a 

 little after the sunspot minimum, while the reverse is the case for all 

 stations in Western Siberia and Russia. The range of time for which 

 these relations have held good is, however, so restricted, that we cannot 

 do more than simply record them, and wait for further confirmation. 



It seems curious that some barometric observations show more rela- 

 tionship to the longer sunspot period, which is so well marked in the 

 aurora borealis. Wolf has first pointed out that the excess of the atmo- 

 spheric pressure in July over that in June decreased from 1770 until about 

 1805, then increased again till shortly after 1833, decreasing from that 

 time to 1860. 



The daily variation of the barometer has been investigated by Horn- 

 stein, and also seems to show a long period, having its maxima and. 

 minima in good agreement with the corresponding phase of the long 

 period of the aurora borealis. It would not be wise to attach too great a 

 value at present to these coincidences. 



A very interesting point has been brought to light by Mr. Joseph 

 Baxendell, 5 of Manchester. He finds, in the first place, that, as was to 

 be expected, the barometer stood on the average higher when the wind 

 came from the north, east, or south-east, than when it blew from the south- 

 west, west, or north-west. 



He next compared together these differences in different years. In 

 the second horizontal row of the following table we give the difference in 

 pressure during easterly winds (north-east, east, and south-east) on the 

 one hand, and westerly winds on the other. It is seen that this difference 

 was greatest in 1860, then gradually decreased till 1867, and then was 

 again greater in 1868. This agrees well with the variation in the num- 

 ber of sunspots which took place during the same time, as is seen by 

 comparison with the numbers given in the fourth horizontal row, which 

 indicate Wolf's sunspot numbers. 



1858 1859 18G0 1801 18G2 1863 



+ 0-190 +0141 +0-226 +0-0CI +0073 +0012 



+ 0-221 + 0-238 +0-231 +0'22!i +0'109 0-103 



5o-2 i'U-3 y±-» 77-7 blO 4.3-i 



L864 18G5 1860 18G7 18G8 



-0-014 -0077 -0-05:s -0-150 +0-09 



0122 0-083 0-038 066 0-074 



45-2 31-4 147 SS " ~~36lT~ 



1 Nature, vol. xviii. p. 567 (1878). - Ibid, vol, xix. p. 6 (1878). 



3 Ihid. vol. xx. p. 29 (1879). « Ibid. vol. xxi. p. 477 (1880). 



5 Proc. Manchester Phil. Sue. xi. 1872, p. 122. 



