By Prof. M. B. GOFF.

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FOR JULY.

THE SUN.

We now enter upon what is usually called the “heated term,” in earnest. The “Dog Days” are upon us, that is, we say they are; but the statement is a somewhat doubtful one. We have the story that the ancients regarded the Dog Star, Sirius, in the constellation Canis Major, as the source of “unnumbered woes,” because it rose a short time before the sun about the season of their year that the hot weather set in, and diseases incident to their climate more than usually prevailed. It is said that they estimated this period as continuing for the space of forty consecutive days, beginning twenty days before, and continuing twenty days after what was called the heliacal (that is, rising just long enough before the sun to be visible) rising of the Dog Star. Now, the difficulty we moderns find in fixing the limits of these days is this: The heliacal rising of the star for any one place can readily be found; but when determined for one place, it would not suit for another in a different latitude. Besides, the right ascension of Sirius, on account of the precession of the equinoxes, is constantly increasing, and hence for the same place these days fall later each year, in the course of time occurring even in mid-winter. Almanac makers, when they notice them at all, seem to take the liberty of treating them to suit their own convenience. For example, one of this year’s publications announces that “Dog Days” begin on the 21st of July, and end on the 30th of August, making, as we see by including one extreme date, altogether the forty days claimed by the ancients. But in this latitude, on the former date, the star rises at 5:43 a. m., one hour and five minutes after, and on the latter date at 3:06 a. m., two hours and twenty minutes before sunrise. Others fix the time from July 3rd to August 11th (forty days), without any respect to the rising of Sirius, which on the former date appears above our horizon at 6:51 a. m., or two hours and seventeen minutes after, and on the latter date at 4:18 a. m., forty-nine minutes before sunrise. Others, again, making an effort, we presume, to adapt them to our climate, regard them as continuing only thirty-two days, namely, from July 24th to August 24th. Taking it all in all, we may as well leave them to the Egyptians and Ethiopians, among whom the ideas in regard to them seem to have originated, as a superstition of the past ages, taking our “heated term” at its usual time, July and August, and throwing our “Dog Days,” as some do physic, “to the dogs.”

Whether we account for it by the extreme heat or not, it is nevertheless a fact that the sun lags along behind our clocks during this entire month; on the 1st, not reaching the meridian till 12:03:41 p. m.; on the 15th till 12:05:44 p. m., and on the 30th till six minutes and nine seconds after noon. The time of the sun’s rising on the 1st, 15th and 30th, is 4:33, 4:43 and 4:56 a. m.; and the time of setting on the same dates is 7:34, 7:29 and 7:17 p. m., respectively. The 30th day of this month will be about forty minutes shorter than the 1st, the latter being fifteen hours one minute, and the former fourteen hours and twenty-one minutes in length. The time from daybreak to the end of twilight is, on the 1st, 19 hours 24 minutes. Sun is due west on the 30th at 5:29 p. m. Its greatest elevation above the horizon in latitude 41° 30', is 71° 33?'.

THE MOON

Exhibits the following phases: Full moon, 5:02 a. m. on the 8th; last quarter, 4:30 p. m. on the 15th; new moon, 7:46 a. m. on the 22nd; first quarter on the 29th, at 4:53 p. m. On the 1st it sets at 12:11 a. m., and on the 30th, at 11:51 p. m. On the 15th, rises at 11:32 p. m. On the 4th, at 7:54 a. m., and again on the 31st at 11:00 p. m. it is at its maximum distance from the earth. On the 20th, at 1:36 a. m. is nearest the earth. Its greatest elevation, equal 67° 13?', occurs on the 19th; and its least elevation, amounting to 29° 42?' on the 5th.

MERCURY.

This planet will be morning star till the 13th, after which it will be evening star till the end of the month. It rises on the 1st at 3:41 a. m.; sets on the 15th at 7:41 p. m., and on the 30th at 8:07 p. m., on which latter date it is possibly visible to the naked eye. Its motion during the month is direct, and amounts to 62° 30' 31.5. On the 17th at 6:00 a. m. it is nearest the sun; on the 12th at 1:00 a. m., 6° 20' north of Venus; on the same date, at midnight, is in superior conjunction with the sun; that is, it is in a line with the earth and sun, and in the order, Earth, Sun, Mercury; on the 23rd, at 3:00 a. m., 1° 10' north of Jupiter; and on the 23rd, at 7:05 a. m., 6° 30' north of the moon. Diameter decreases from 5.6 to 5.4.

VENUS.

A view of Venus during this month through a telescope of moderate power would be an interesting sight, since she now presents the appearance of our moon in its first or last quarter, and thus seems quite different from the simple star that is visible to the naked eye. She will be evening star till the 11th, at which time she reaches her inferior conjunction, that is, reaches a point directly between the earth and the sun; after which she will be morning star, not only to the end of this month, but for several successive months. Of course, for a number of days both before and after conjunction, she will, on account of her proximity to the sun, be invisible. We shall miss her “beaming countenance,” but we know that she will appear again. On the 1st she sets at 8:14 p. m., and rises on the 15th at 4:38 a. m., and on the 30th at 3:17 a. m. On the 21st at 6:28 a. m. she is 1° 11' south of the moon; and on the 29th at 11:00 a. m., farthest from the sun.

MARS

Has from the 1st to 30th a direct motion of 15° 36' 32, and although much reduced in apparent diameter, is still quite a prominent object in the evening sky, following westward in the wake of Jupiter. His diameter decreases from 5.6 to 5.2. He rises in the forenoon, and sets as follows, in the evening: On the 1st at 10:47; on the 15th at 10:11; and on the 30th at 9:31. On the 26th at 5:04 p. m. he is 2° 5' north of the moon.

JUPITER

Will be evening star throughout the entire month, though at its close approaching so near the sun as to be scarcely visible. He sets at the following times: On the 1st at 9:08; on the 15th at 8:22; and on the 30th at 7:33 p. m. His motion is direct, and amounts from the 1st to the 30th, to 6° 17' 55. Diameter decreases from 30.2 to 29.6. On the 23rd, at 3:00 a. m. is 1° 10' south of Mercury; and on the same day at 6:34 a. m. is 5° 21' north of the moon.

SATURN.

This planet is now one of our morning stars, rising on the 1st at 3:06, on the 15th at 2:17, and on the 30th at 1:25 a. m. Motion direct, amounting to 3° 32' 30¾. Diameter increases from 15.6 to 16.2. On the 19th, at 1:01 p. m. is 3° 2' north of the moon.

URANUS,

Whose direct motion during the month is estimated at 1° 3' 26, continues its role as evening star, setting at the following times: On the 1st at 11:10; on the 15th at 10:16; and on the 30th at 9:17 p. m. On the date last named, Beta Virginis will be only two minutes south of and will set at the same time as the planet. On the 19th, at 2:00 p. m., Uranus will be eleven minutes north of Mars; and on the 26th, at 9:57 a. m. will be 2° 43' north of the moon.

NEPTUNE

Scarcely affords this month material for comment. Its diameter at present appears to be 2.6. Its motion is 40' 35, and is direct. On the 1st it rises at 1:44 a. m.; on the 15th at 12:49 a. m.; and on the 30th at 11:45 p. m. At 5:27 p. m., on the 17th, it will be 1° 11' north of the moon.

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FOR AUGUST.

The mid-day shadows lengthening northward indicate to us northern folks that “Old Sol” has departed on his annual southern tour. He now cuts off the day at both ends, on the 1st rising 25 minutes later and setting 20 minutes earlier than on the 1st of July. His change in declination since June 20th, beginning of summer, till August 31st, will be a little over 15°, and the decrease in the length of the day for the same time, will be a trifle less than two hours. He will come to the meridian on the 1st, at six minutes and two seconds after 12:00; on the 15th at four minutes and eight seconds after 12:00; and on the 30th at sixteen seconds after 12:00. On the same dates he will rise at 4:58, 5:11, and 5:26 a. m., and set at 7:14, 6:57, and 6:35 p. m. Daybreak will occur at 3:05, 3:23, and 3:44 a. m., and twilight will end at 9:07, 8:45, and 8:16 p. m. Greatest elevation in latitude 41° 30' will be 66° 18?'.

THE MOON’S

Phases occur in the following order and time: Full moon on the 6th, at 5:58 p. m.; last quarter on the 13th, at 10:00 p. m.; new moon on the 20th, at 4:46 p. m.; and first quarter on the 28th, at 10:34 a. m. The moon rises on the 15th at 12:39 a. m.; and sets on the 1st and 31st at 12:30 and 12:43 a. m., respectively. On the 16th at 11:00 a. m., nearest the earth; on the 28th, at 5:30 p. m., farthest from the earth. Its greatest elevation, 67° 4', occurs on the 15th, and its least, 29° 50.8' on the second day of the month.

MERCURY

Reaches its greatest elongation east (27° 21'), very nearly its maximum distance from the sun; yet the opportunity for observation is not so favorable as on many occasions when the elongation is several degrees less. And the reason is, that the planet is now moving southward, is in fact on the 23rd, the date of its greatest eastern elongation, 1° 16' south, while the sun is still 11° 9' north of the equator, and sets, therefore, only about fifty minutes later than the sun. The time of the planet’s setting is for the 1st, 8:07 p. m.; 15th, 7:53 p. m.; 30th, 7:16 p. m. It has a direct motion of 32° 49' 39. Its diameter increases 2.6, namely, from 5.6 to 8.2. It is farthest from the sun on the 20th, at 6:00 a. m. On the 23d, at 8:00 a. m., 3° 5' south of Uranus.

VENUS

Again reaches a position of greatest brilliancy on the 17th, and during the entire month will be an object of interest to early risers. On the 2nd she will appear stationary; and on the 17th at 4:37 p. m. will be 23 minutes south of the moon. Her diameter will decrease from 49 on the 1st to 31.8 on the 30th. Her time of rising will be as follows: On the 1st, at 3:08; on the 15th, at 2:23; and on the 30th, at 2:01 a. m.

MARS

Seems to grow “small by degrees and beautifully less,” his diameter at the close of the month being only 4.8. He sets at 9:25 on the evening of the 1st; at 8:51 p. m. on the 15th, and at 8:13 p. m. on the 30th. On the 24th, at 10:29 a. m. he is only 10' south of the moon.

JUPITER

With his huge form and accompanying satellites fare the fate of all “lights” terrestrial and celestial, and his “glory” sinks into insignificance beside that of his “ruling power,” as he on the 7th, at 1:00 p. m. comes in conjunction with the sun and changes his relation from that of an evening to that of a morning star. On the 1st he sets at 7:26 p. m.; on the 15th rises at 4:44 a. m.; and on the 30th rises at 4:02 a. m. Is in conjunction with and 5° 8' north of the moon at 2:36 on the morning of the 20th.

SATURN,

Another of our morning stars, rises on the 1st and 15th at 1:18 and 12:28 a. m., respectively; and on the 29th, at 11:34 p. m. His diameter increases from 16.2 to 16.8. His motion is direct, amounting to about 2° 43'. He can be found a little north of Zeta, the star denoting the extremity of the northern horn of the constellation Taurus. On the 16th, at 12:41 a. m. will be 3° 17' north of the moon.

URANUS,

Which on the 30th of last month was so near Beta Virginis, has moved about 1° 35' farther to the east; but can be more readily pointed out by its proximity to this than to that of any other star. Uranus is an evening star, setting at the following dates: 1st, at 9:10 p. m.; 15th, at 8:17 p. m.; 30th, at 7:20 p. m. Diameter, 3.6. On the 22nd, at 9:35 p. m. is 2° 25' north of the moon; and on the 23rd is 3° 5' north of Mercury, at 8:00 a. m., an hour at which neither planet can be seen by the unaided eye.

NEPTUNE,

Last, but by no means least of the heavenly bodies, gives us this month more than the usual variety, which, however, is not saying much for the spice it affords. But it has a direct motion of 10° 42', and a retrograde motion of about 1'. On the 14th, at 11:00 p. m. it is in quadrature (90° west of the sun); on the 26th, at 5:00 a. m. it is stationary, and on the 14th is 1° 25' north of the moon.

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FOR SEPTEMBER.

THE SUN

“Crosses the line” on the 22nd at 10:13 a. m.; in other words, enters the sign Libra, giving us a clearly marked time for the beginning of another season—Autumn—which lasts 89 days, 18 hours, 29 minutes, nearly. His greatest elevation above the horizon in latitude 41° 30' is about 56° 28', an indication that his time above the horizon is decidedly shorter than it was last June, when his elevation was a little more than 71° 57'. And this also is confirmed by the times of his rising and setting, which are as follows: On the 1st, rises at 5:28 a. m., and sets at 6:32 p. m.; on the 15th, rises at 5:41 a. m., and sets at 6:09 p. m.; on the 30th, rises at 5:56 a. m., and sets at 5:43 p. m. Theoretically, on the 22nd, the day and night should each be exactly 12 hours long; but practically the daylight is longer than the darkness, on account of the refraction of light by the earth’s atmosphere, which has the effect of bringing into view the sun before it actually “rises,” and of detaining it in sight after it has “set.” Twilight also affords us so much additional light that we may safely assert that in any given place on the earth’s surface there is much more “daylight” than “night.” For example, on the 30th, daybreak occurs at 4:22 a. m., and twilight ends at 7:18 p. m., thus giving three hours and nine minutes in which to lengthen our daily toil, if we choose so to do. In the same latitude, and in different latitudes, as was shown in The Chautauquan for June, the length of twilight varies, so that in some instances the entire night is only twilight. Are these facts any indication that we should be awake longer than we sleep? or that we should labor more hours than we rest? Should we be always

THE MOON.

The man who attends to his neighbor’s business generally has his hands full. So has the man who attends to the motions of his neighbor, the moon. By the time he investigates her parallax, diameter, distance, revolution on her axis, sidereal and synodic revolutions, the form of her orbit, her phases, discusses her physical properties, determines her heat, height of her mountains, size of her craters, describes her librations, decides upon the effect she exercises on the weather, and a thousand more or less of other things, he had better settle down and make it the business of his life. And if he does, he may be able to show some good results of his labors. It is well for us that not any single man, but many men, have given our satellite so much attention; for it is only by the uniting of the results of their researches that we are enabled with comparative ease to predict what business our neighbor has on hand, and when and how she will perform her duties. Thus, we find that she will this month present the following phases: On the 5th, at 5:47 a. m., full; on the 12th, at 3:08 a. m., last quarter; on the 19th, at 4:29 a. m., new moon; on the 27th, at 5:13 a. m., first quarter. She will rise on the 15th at 1:39 a. m., and set on the 1st and 30th at 1:36 a. m. and 1:18 a. m., respectively. At 12:54 p. m., on the 10th, will be nearest the earth (in perigee), and on the 25th, at 12:54 (exactly fifteen days later), farthest from the earth, or in apogee. Greatest elevation on the 12th, amounting to 66° 54?'; least elevation on the 26th, equaling 30° 8'.

MERCURY

Will be evening star till the time of its inferior conjunction on the 19th, after which it will be morning star. It appears stationary on the 6th, and also again on the 28th. On the 19th it is 1° 34' south of the moon. Its apparent diameter increases from 8.4 to 10.4, and then diminishes to 7.4 at the close of the month. It sets on the 1st at 7:08 p. m.; on the 15th at 6:05 p. m.; and rises on the 30th at 4:37 a. m.

VENUS

Reaches her greatest distance east of the sun, 46° 6', on the 29th, at 7:00 a. m. Her diameter decreases from 30.8 to 22; and her direct motion amounts to 27° 40' 55.2. On the 15th, at 1:08 p. m., she is 2° 26' north of the moon. She rises on the 1st, 15th and 30th, at 2:00, 1:59, and 2:11 a. m., respectively.

MARS

Still retains his position as evening star, setting on the evening of the 1st, 15th and 30th in the same order, at 8:08, 7:36 and 7:11. His diameter decreases from 4.8 to 4.6. Direct motion amounts to about 18° 40' 12 of arc. He is 2° 20' south of the moon on the 22nd, at 6:48 a. m.

JUPITER

Is morning star, rising at the following times: 1st, at 3:55 a. m.; 15th, at 3:16 a. m.; 30th, at 2:32 a. m. Its motion is direct, and equals about 5° 45' 14 of arc. Its diameter increases one second, being on the 30th 31. On the 16th, at 8:30 p. m. is 4° 55' north of the moon.

The satellites of Jupiter, four in number and designated as 1, 2, 3, 4, outwardly from the planet, are frequently used to find the longitude. To do this, however, requires the use of a telescope. By observing the time at which one of these satellites passes into or emerges from the shadow of its primary, and comparing this time with the recorded time of the same event in Washington City, for example, one can determine whether he is east or west of this city, and how many degrees. On the 14th No. 1 enters the shadow of Jupiter at 4:46 a. m., Washington mean time. Suppose the observer at Allegheny Observatory should note the same event as occurring at exactly 57 minutes 50.84 seconds after four, Allegheny Observatory time. He would find the difference of the two times to be 11 m. 50.84 s., which reduced to longitude by multiplying by 15 (since one hour of time equals 15° of arc) gives the difference of longitude 2° 57' 40.3. And since the ingress occurred at Allegheny Observatory at an earlier hour (by its local time) than by Washington local time, it follows that the latter place is 2° 57' 40.3 east of the former.

SATURN

Continues as in the last two or three months among the morning stars, rising as follows: 1st, at 11:22 p. m.; 15th, at 10:30 p. m.; 30th, at 9:33 p. m. His diameter increases from 16.8 to 17.8. His motion is direct, and equal to 1° 7' 25. On the 12th, at 9:17 a. m. he is 3° 28' north of the moon; and on the 16th, at 10:00 a. m. 90° west of the sun, that is, in quadrature.

URANUS

Makes a direct motion of 1° 43' 22 during the month. Its diameter reaches its minimum for the year, 3.48, on the 20th. On the 19th, at 4:13 a. m. it is 2° 14' north of the moon. It begins the month as an evening, but closes it as a morning star. It is, however, most of the time above the horizon in daylight. On the 1st it rises at 6:54 a. m. and sets at 7:06 p. m.; on the 30th it rises at 5:24 a. m., and sets 5:30 p. m.

NEPTUNE,

On the contrary, is above the horizon most of the month during the night, rising on the 1st at 9:37 p. m.; on the 15th at 8:43 p. m.; and on the 30th at 7:44 p. m. Its motion is about 20' 52 retrograde, and its diameter nearly constant at 2.6. On the 10th, at 5:20 a. m., appears 1° 33' north of the moon.