point: "Now, I think I may conclude that from the point of view of climatology or meteorology, in the present state of these sciences, the hypothesis of CROLL seems to be wholly untenable, as well in its principles as in its consequences." * It seems that the great advantage which CROLL's hypothesis promised to geologists, viz: of giving them a natural chronology, predisposed them in favor of its acceptance. But this circumstance, which at first appeared advantageous, seems with the advance of investigation rather to militate against the theory, because it becomes more and more impossible to reconcile the chronology demanded by CROLL'S hypothesis with the facts of observation. I trust that after what has been said the theory proposed in the foregoing pages will prove useful in explaining some points in geological climatology which have hitherto proved most difficult to interpret. PLANETARY PHENOMENA FOR MARCH AND BY PROFESSOR MALCOLM McNeill. MARCH. The Sun "crosses the line" and spring begins just after midnight, March 19-20 P. S. T. Mercury is a morning star, having passed greatest west elongation on February 15th. At the beginning of the month it rises not quite an hour before sunrise, and may possibly be seen if the weather conditions are very favorable, but its distance from the Sun grows less throughout the month, and it comes to superior conjunction on April 1st. Venus is an evening star, having passed its greatest east elongation in February. During the month it draws a little. nearer the Sun, but sets more than three hours after sunset at the end of the month. On March 21st it comes to its maximum brilliancy, and all through the month it will be visible to the naked eye in full daylight, if the sky is clear and free from haze. Mars is still a prominent object in the western sky in the evening, and does not set until after midnight. During the * DE MARCHI, 7. c. p. 166. month it moves about fifteen degrees eastward from the constellation Taurus into Gemini. On March 1st it is about three degrees south of the second magnitude star ẞ Tauri. The planet has lost very much in brightness, but is still conspicuous. At the end of the month its distance from us is about 130,000,000 miles, two and and one-half times as far away as it was at opposition in December. Jupiter passed opposition on February 23d, and is above the horizon practically the whole night throughout March. It is retrograding, moving westward and northward about three degrees during the month toward the first magnitude star Regulus (a Leonis), and at the close of the month is about three degrees east of the star. Saturn rises two hours earlier than during the corresponding period in February, and toward the close of the month is well above the horizon before midnight. It is in the constellation Scorpio and moves slowly eastward and then begins to move westward, but the total change of position is only a fraction of a degree. It is about one degree north of ẞ Scorpii. The rings are in good position for observation, being well out toward their maximum opening. Uranus is near Saturn about two degrees west and one degree thirty minutes south, and moves in about the same way but not as fast. Neptune is in Taurus and sets at about midnight. APRIL. Mercury passes superior conjunction on April 1st, and through the rest of the month is an evening star reaching greatest east elongation on the morning of April 28th. From the middle of the month it sets more than an hour after the Sun, and at the end of the month it sets nearly two hours later. This is the best time of the year for seeing the planet as an evening star. Venus sets about three hours later than the Sun on April 1st; but it rapidly approaches the Sun and passes inferior conjunction on the morning of April 28th. It will not be easy to see after April 20th. Venus and Mercury are in conjunction on the morning of April 17th, Mercury being five degrees south. Mars still sets after midnight. During the month it moves about seventeen degrees eastward in the constellation Gemini, and at the close is south of Castor and Pollux (a and ß Gemin orum), the distance from the nearer star not being greatly dif ferent from their distance apart. The planet makes a very near approach to the third magnitude stare Geminorum on the morning of April 8th. The least distance is only two minutes, and to the naked eye the star will be lost in the glare of the planet, but the phenomenon will occur while they are below our horizon. jupiter is above the horizon until long after midnight. It is in the constellation Leo, and moves slowly westward about one degree toward the first magnitude star Regulus, until it stops and begins to move eastward on April 26th. It is about two degrees east of Regulus at the end of the month. Saturn rises at a little after 8 P.M. at the end of the month. It is in the constellation Scorpio, and moves about two degrees westward during April away from the second magnitude star ẞ Scorpii, which is a little east and south of the planet. Uranus is about two degrees west and the same amount south of Saturn. The distance west diminishes slightly, and the distance south increases slightly during the month. Neptune is in the constellation Taurus and sets before midnight. Occultations. The Moon occults the Pleiades group on the evening of April 5th. The Moon is then about four days old, and it will be a fine opportunity for seeing the disappearance of the stars at the dark limb. The times vary so for different parts of the country that it is not worth while to try to give any here. EXPLANATION OF THE Tables. The phases of the Moon are given in Pacific Standard time. In the tables for Sun and planets, the second and third columns give the Right Ascension and Declination for Greenwich noon. The fifth column gives the local mean time for transit over the Greenwich meridian. To find the local mean time of transit for any other meridian, the time given in the table must be corrected by adding or subtracting the change per day, multiplied by the fraction whose numerator is the longitude from Greenwich in hours, and whose denominator is 24. This correction is seldom much more than 1". To find the standard time for the phenomenon, correct the local mean time by adding the difference between standard and local time if the place is west of the standard meridian, and subtracting if east. The same rules apply to the fourth and sixth columns, which give the local mean times of rising and setting for the meridian of Greenwich. They are roughly computed for Lat. 40°, with the noon Declination and time of meridian transit, and are intended as only a rough guide. They may be in error by a minute or two for the given latitude, and for latitudes differing much from 40° they may be several minutes out. |