The movements of the magnetic needle are affected during the prevalence of "sun spots"and fluctuations occur called magnetic storms during the disturbances in the sun's atmosphere. There are many records of these phenomena; one recorded in 1859 on the Ist of September is quoted as conclusive. Great spots were seen on that day and were being observed by two celebrated astronomers far distant from each other suddenly a luminous cloud broke out in the vicinity of the largest spot and_travelled with great velocity across the face of the sun and only about five minutes elapsed between its first appearance and its disappearance. At the same time on our earth a magnetic storm was in progress; the three self-recording needles at Kew showed a remarkable oscillation. Auroras were visible all the world over to within 20° of the equator. In many places telegraphic communication ceased and in one station the apparatus was set on fire. Professor Stewart in an article in Nature vol. xvi, 1877, says that the planets influence the magnetic needle indirectly through their disturbing action on the sun and that the daily range of the magnet freely suspended at Kew Observatory is sensibly greater about the time that Mercury is nearest the sun or Venus and Merency come together in position, S1ZB OF THE "spoTs."
The sun spots" show us that the centre of our solar system revolves on its axis in 25.23 days, some spots having remained so long on the sun as to be counted seventeen times. In different solar latitudes the spots rotate in different, crieds and are depressions below the level of the photosphere caused by violent downrushes of comparatively cool vapour. Generally speaking they are com of dark central nucleus surrounded by an umbra between which and the blending of the spot with the atmosphere isa penumbra, both umbra and penumbra being less dark than the nucleus, As th" spot apparently moves from the centre of the sun to the sides we lose sight of the dark nucleus proving that it must be a depression; the spectroscope also proves the same by its decrease of light, showing that the spots are regions of absorption in which there is pereipltation of cool matter accompanied rotatory action. The largest "sun spots" that have been recorded are recent ones. One group in November 1882, another in February 1892 (the largest ever photographed at Greenwich), and one in the present year. In Febru: ary the central spot was 100,000 miles in length and about 65,000 in breadth. As usual the magnetic needle was disturbed and beautiful aurora seen all over the world. In conclusion, it is not argued that the "sun spots" exercise any influence on the terrestrial phenomena, but that the ''spots" are evidence of the disturbances that are soing on in the sun. It is this action that affects our planet and most likely the other planets as well.
Wu. J. Larace.
Text read from the printed page and cleaned; old type leaves the occasional error.