observations thus made Messrs. F. H. BIGELOW and W. H. PICKERING have made important studies as to the possible causes of the phenomenon. I now propose to men of science to conduct the observations in future eclipses by geometrically searching for the position in space of the producing elements of such bands; or, perhaps, they may have a luni-solar origin, owing to the decomposition effected by the edges of the Moon upon the rays of the thin solar sickle at the proximities of totality.

To determine the position of such elements, three different planes with two (one vertical and another horizontal), as per descriptive geometry, would be enough. That is the method followed by us of determining in the eclipse of August 30, 1905, at Soria, Spain, the position of said elements, which were found to be in a plane nearly vertical (88° to 99° in 5 seconds), forming with the observation vertical plane, placed from east to west, an angle less than 45°. From these observations we have deduced the great convenience of employing several other planes on which to mark the traces of the undulating bands, and our apparatus to observe the eclipse in 1912 will be constituted (see figure), first, of a horizontal plane, A B, at the height of the arms of the observer, who will be situated at O; second, the vertical plane, CD, placed from north to south; third, another vertical plane, EF, from east to west; fourth, another, G H, azimuthal to the Sun at the moment of totality; fifth, another, IJ, perpendicular to the latter; sixth, another, KL, in the direction of the wind, moved by the weathercock, V, which may be made immovable at the moment of observation. The observer, at O, will mark in all these planes the respective orientation of the bands at least once before and once after the total phase.

In the prolongation of these planes will be placed six observers, who will mark the said orientation of the bands, each in his respective plane, as a check on the observations.

Six other observers will measure the width of the bright parts between the bands by comparison with the respective scale ribbons aa, bb, cc, dd, ee, ff. Each of these ribbons is mounted upon two rollers forming an endless chain. The rollers are so mounted that the ribbons may easily be placed perpendicularly to the bands.

In the linen scale-ribbon are drawn black bands measuring 2cm, separated by increasing series from 2 to 30cm. The zones coinciding in width with the separation-zones will be marked with a pencil between the bands. Two other observers will measure the width of the bands by comparison with a pasteboard with painted bands separated by one half centimeter. Another six could study the coloration of the bands by means of special pasteboards with painted bands in several colors, black, earthy, gray, etc.

With the data of the first seven observers, and the geometrical studies of every two or every three of the six planes, we shall have all the necessary elements to geometrically calculate the position in space of the generating elements of the undulating bands, and we shall be able to advance most confidently conclusions about the true cause of so interesting a phenomenon. MADRID, September 3, 1905.

The vernal equinox, the time when the Sun crosses the equator from south to north and spring begins, is on March 21st, 5 A. M. Pacific time.

Mercury is an evening star on March 1st, but is too near the Sun to be seen, setting only a little more than half an hour after sunset. The distance from the Sun increases rapidly; by the middle of the month the planet remains above the horizon more than an hour and a half after sunset, and can be easily seen in the evening twilight for a week or more before and

after that date. It reaches its greatest eastern elongation (18° 31′) on March 18th. This greatest elongation is much smaller than the average, as Mercury is at the time only six days from perihelion, having passed that point on March 12th. After passing greatest elongation the planet draws near the Sun, passing conjunction and becoming a morning star on April 4th. After that, it recedes from the Sun, and by the end of the month has nearly reached greatest west elongation. It will then rise a little less than an hour before sunrise, and may possibly be seen in the morning twilight. On March 27th Venus and Mercury are in conjunction, the latter being 4° 46′ north. They are, however, rather too near the Sun at the time to be easily seen.

Venus passed superior conjunction with the Sun and became an evening star on February 13th, but does not get far enough away from the Sun to be easily seen until after the middle of March. On April 1st it remains above the horizon about an hour after sunset, and this interval is increased about half an hour during the month. Its greater brightness, even in its present unfavorable position, allows it to be seen much nearer the Sun than is the case with Mercury. Toward the close of the month Venus, Mars, and Jupiter are all in the same quarter of the heavens in the order of distance from the Sun as named, but none of the three reach conjunction with each other until May.

Mars is also an evening star, and sets a little earlier than during January and February, at 8:58 P. M. on March 1st and at 8:40 P.M. on April 30th. Its apparent distance from the Sun diminishes from 35° on March 1st to 19° on April 28th, and it moves 42° eastward and 14° northward among the stars from Pisces through Aries and into Taurus. At the end of April it lies between the Pleiades and the first-magnitude red. star Aldebaran, the brightest star in the constellation Taurus. Its actual distance from the Earth is still increasing, although not as rapidly as it has for some months, and the increase will continue at a diminishing rate until the latter part of July. By the end of April its brightness will be within about twenty per cent of the minimum; but it will still be brighter than the Pole Star and may be seen as long as it remains above the horizon, somewhat more than an hour after sunset.