ANNUAL OF SCIENTIFIC DISCOVERY. 



ments of the great currents of the air produced by alterations in the 

 earth's magnetic condition. If the larger part of the diiference of 

 temperature is due to the latter mode of action, we might expect that 

 during the warmer half of the period the mean direction of the wind 

 at any given station would be sensibly different from that during the 

 cooler half; and also, that the epochs of maximum and minimum 

 temperature would not be the same at all parts of the earth's surface. 

 Both of these conclusions are borne out by the results given in the 

 paper. Thus at St. Petersburg, in 1859, the mean direction of the 

 wind on maximum days was S. 54 W., and on minimum days S. 73 

 W. or 19 more to the west of South ; and atSitka, on the Northwest 

 Coast of North America, in 1851, the mean direction on maximum 

 days was S. 32 W., and on minimum days S. 56 W., the difference 

 being 24. As striking instances of the differences in the epochs at 

 distant stations, it may be stated, that in 1859 the epoch of maximum 

 at St. Petersburg corresponded precisely with the epoch of minimum 

 at Madras ; and that at Pekin, in 1851, the epoch of minimum was 

 exactly coincident with the epoch of maximum at Sitka. 



Changes in the amount of heat received from the sun, sufficient to 



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produce the variations of temperature observed at any given station, 

 would no doubt affect the movements of the great currents of the at- 

 mosphere, though not to the extent indicated by the observations ; 

 but it is difficult to conceive that they could produce the differences in 

 the epochs which are found to take place. We may therefore fairly 

 conclude that the action of the supposed ring of nebulous matter 

 is principally of a magnetic, and but slightly of a thermal character. 



Adopting, for the present, the maximum and minimum values of 

 the temperature period as being determined with greater accuracy 

 than those of the magnetic period, the greatest and least values of the 

 sidereal period of revolution of the ring will be 29'12 and 22'08 days 

 respectively. From these numbers we find that the greatest distance 

 of the ring from the sun is O185, the radius of the earth's orbit being 

 taken as unity; the least distance, 0*154; and the mean O169. 

 Taking Mr. Hind's value of the mean distance of the earth from the 

 sun, namely, 91, 328,1)00 miles, we have: Greatest distance of the 

 ring, 10,921,000 miles ; least distance of the ring, 14,068,000; mean 

 distance of the ring, 15,494,500; and the range of movement to and 

 fro in a radial direction, 2,853,000 miles. The greatest attractive 

 force of the sun on the ring being taken as unity, the least will be 

 0'691. The difference is therefore nearly^ of the maximum amount. 

 It will be evident that this difference may be regarded as a measure 

 of the forces which are concerned in the production of the solar spots. 



The results of the elabor ite invesiigations of the motions of the pl.inet 

 Mercery, made by Leverrier, led that accomplished mathematician to 

 aitri'mte a certain unexplained exce.-s in the motion of its perihelion to 

 the action of a disturbing bodv* circulating round the sun within the orbit 



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of Mercury ; and, fro.n a discu sion of the ;>rob.ible mass of the disturbing 

 b):ly, he concluded that it could not be concentrated in a single pla <et, 

 and th.it it consisted of -a ring of small bodies similar to that which is 

 known to exi.^t between the orbits of Mars and Jupiter ; and it is re- 

 marka ile that the mean distance, which he seemed to regard as the most 

 probable, is precisely that which the author has found for the ring of 



