The Chautauquan, Vol. 04, July 1884, No. 10

by Chautauqua Literary and Scientific Circle; Chautauqua Institution

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

“Up and doing,

With a heart for any fate,

Still achieving, still pursuing”?

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° 54⅔′; 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.