[Sidenote: Mr. John Allan Broun’s magnetic oscillation-curves; showing that the sun’s magnetic action has lately become more constant. In diagram, curves gradually flatten.] In an interesting communication to ‘Nature’ (January 3rd, 1878), entitled “The Sun’s Magnetic Action at the Present Time,” Mr. John Allan Broun has contributed some magnetic oscillation-curves, deduced from observations made in the Trevandrum Observatory (nearly on the magnetic equator), by which, if confirmed by other observations, it would appear that the sun’s magnetic action has lately become gradually more constant. The curves are three in number,—no. 1 for the years 1855-58, no. 2 for the years 1865-68, no. 3 for the years 1874-77. In no. 1 curve the minimum is very clearly marked by two points corresponding to April 1 and May 1, 1856, and there is little difference in the rapidity with which the curve descends to and ascends from the minimum. In no. 2 curve the epoch of minimum is by no means so well marked; it occurs between the points for April 1 and September 1, 1866. There is also a considerable difference in the rapidity of variation in the descending and ascending branches of the curve. The descent is nearly as rapid as in curve no. 1; but the ascent is very much slower. In curve no. 3 the lowest point is that for December 1, 1875; but it is even now, with points a year and a half later, difficult to say whether this is the minimum or not, the point for January 1, 1877, being only 0·02 (two hundredths of a minute of arc) higher. In this curve the change of range in diurnal oscillation is quite insignificant from November 1, 1874, to April 1, 1877, an interval of three years and five months. In the diagram given by Mr. Broun the curves show themselves gradually flattening, no. 3 being almost a straight line. [Sidenote: Mr. Broun never found an Aurora without a corresponding irregularity in the declination-needle.] Mr. Broun remarks upon the report of Sir George Nares as to the insignificant nature of the Auroræ seen in the Arctic Expedition in the winter of 1875-76, and the accompanying statement that, as far could be discovered, they were totally unconnected with any magnetic or electric disturbance; and states, as the result of his own experience in the south of Scotland, that several of the Auroræ observed by him were of the very faintest kind, “were traces” which he could never have remarked had he not been warned by very slight magnetic irregularities to examine the sky with the greatest attention. Again, in no case had he seen the faintest trace of an Aurora without finding at the same time a corresponding irregularity in the movement of the force or declination-magnet. [Sidenote: Prof. Piazzi Smyth comments on variance in the cycles.]