Page images
PDF
EPUB

The tables make the extent of the penumbra, when least, about 4,500 miles; when greatest, a little more than 7,000 miles. It is very different at different times, varying on account of the distance of the Sun and Moon, but more from the oblique manner in which it often strikes the Earth.

According to the tables in the author's larger work, total darkness in a solar eclipse will never continue in one place more than 5 m. 32 s. The duration will be a little longer, according to the tables of Enfield. Several authors state this duration short of the truth, making it three minutes, or about three minutes. In the June eclipse of 1806, total darkness was considerably short of the greatest possible duration ; yet in the southern part of New Hampshire, the author, by the most careful observation, made it 4 m. 20 s At Sterling, Massachusetts, Robert B. Thomas, the author of the Farmer's Almanac, probably nearer the centre of the shadow as it passed, found the time of total darkness 4m. 45 s.

The beginning of a general eclipse is when the penumbra first touches the Earth ; the ending, when it leaves the Earth. In the same manner, the commencement and end of an eclipse at any particular place, is marked by the approach, or first touching and departure of the penumbra. When the Moon changes in one of her nodes, the penumbra and dark shadow pass over the centre of the Earth, making the longest general eclipse. The duration varies a little with the distance of the Sun; more with the distance of the Moon from the Earth. When the Moon is m apogee, and the Earth in perihelion, it is longest, being then about 6 h. 13 m. The mean duration of a general eclipse is 5 h. 46 m.

The position of the Earth's axis, as seen from the Moon or the Sun, greatly affects solar eclipses. The eclipse of 1806 wilt make a return in 1860, 'visible in the United States. But the position of the Earth's

axis being different, it will be to us far less than it was in its former visit. See this eclipse of 1860, as projected by the author in his larger astronomical work.

What is an eclipse? What heavenly body shines by its own light? What is the form of a planet's dark shadow ? Are the shadows of the planets coextensive with the Sun's light ? Do the primary planets ever eclipse each other? What do eclipse? What is the greatest length of the Earth's shadow ? What is its mean length? Why have we not eclipses at every change and full ? Where must the Moon be in order that there may be an eclipse ? What is the limit of solar, and what of lunar eclipses ? When are lunar eclipses partial ? When are they total ? and when central ? What causes the Moon to be visible when she is eclipsed ? Which are the most frequent, solar or lunar eclipses? Why is a solar eclipse sometimes total and sometimes annular According to calculation, how many annular, and how many total eclipses will be visible in the United States in the present century ? At what times will they happen? What is the Moon's penumbra ? What is the greatest number of eclipses in a year? What is the least ? When two, are they lunar or solar? How are they when seven? In what direction does the line of the Moon's nodes move? In what time does it complete a revolution ? When eclipses happen at one node, how long before they may be expected at the other When the Sun and Moon have been in conjunction at one of the Moon's nodes, how long before they will be in conjunction again near the same node ? Is there a regular period of eclipses ? How long is it? Where do eclipses at the ascending node first strike the Earth ? Where do they pass off? Where do eclipses at the descending node commence and retire ? After an eclipse has completed a series, and left the Earth, how long before it will commence a new series at the same node How many times may an eclipse visit the Earth in one series ? In what number of years is a series completed ? At what node was the memorable eclipse of June 16, 1806 ? When did this eclipse first meet the south pole? When was its last return? Why did it not attract notice ? When will be its next return?. Where will it be visible and total ? When, and at what pole, will this eclipse leave the Earth? How many miles does the dark shadow of the Moon extend on the Earth? What is the extent of the penumbra ? Why is the extent different at different times ? How long will total darkness continue in a solar eclipse ? What was the duration of total darkness in the June eclipse of 1806 ? When does a general eclipse begin and end? When does an eclipse begin and end at a particular place ? What varies a little the duration ? What is the longest continuance of a general eclipse ? What is its mean duration? Has the position of the Earth's axis any effect on solar eclipses ?

. Catalogue of Eclipses visible at Washington, and generally

throughout the United States, extracted from the Author's larger Work. Commencing with the Year 1831, it is continued through the 19th Century.

The time set to solar eclipses is the middle of each eclipse, as seen at Wash

ington ; to lunar, the minute of opposition. Both are reduced to apparent time.

Year.

Species.

Month. D. H. M. A. P. M.

Remarks.

July

1831 Feb. 12 O 35 P. M. Annular over a large S. E. secDAug. 23 4 57 A. M.

[tion of the Union. 1832 Feb. 1 5 10 P. M.Visible in the western parts of July 27 7 34 A. M.

[the Union. 1833 Jan.

6 2 48 A. M.

1 7 32 P. M. Nearly total. Dec. 26 4 30 P. M. Total. 1834

D

June 21 3 13 A. M.Total.
Nov. 30 2 38 P. M.

Dec. 15 11 50 P. M.
1835
1836 May 1 3 6 A. M.

o May 15 8 14 A. M.

Oct. 24 8 22 A. M. Visible in Missouri Territory. 1837Oct. 13 6 29 P. M. Total. 183815 April 9 9 0P. M.

Sept. 18 4 32 P. M. Annular in Virginia. 1839 1840 Aug. 13 2 9A. M. 1841 Feb. 5 8 49 P. M.Total.

DAug. 2 4 49 A. M. Total. 1842 July 22 5 43 A. M. Visible in Astoria and other 1843 Dec. 6 ņ 7 P. M. Very small. [western regions. 1844 Nov. 24 6 51 P. M.Total.

Dec. 9 4 19 P. M.Small. 1845 May 6 A. M. Sun rises a little eclipsed.

Nov. 13 8 7P. M. 1846 0 April 25 0 6 P. M. 1847 1848 Sept. 13 1 23 A. M. Total. 1849 Mar. | 8 7 48 P. M. 1850 1851 July 13 2 8A. M.

July 28 8 11 A. M.

Year.

Month. D. H. M. A. P.M.

Remarks.

1852 Jan. 7 1 3 A. M.Total.

Dec. 26 A. M. Begins 6 h. 28 m. 1853 Jan. 21 1 3 A. M.Small. 1854 Nov. 4 4 22 P. M. Very small. Visible in N. E. 1855 ) May 1 11 6P. M.Total.

Oct. 25 2 42 A. M. Total. 1856 April 20 4 10 A. M.

Oct. 13 6 12 P. M. 1857 1858 Feb. 27 4 55 P. M. Moon rises partially eclipsed.

Mar. 15 6 16 A. M. 1859 Feb. 17 5 36 A. M. Total.

July 29 5 44 P. M.Small. 1860 Feb. 6 9 17 P. M.

July 18 7 55 A. M. 1861 Dec. 17 3 9A. M.

Dec. 31 7 45 A. M. 1862 June 12 1 18 A. M. Total.

Dec. 6 2 43 A. M.Total. 1863 June 1 6 30 P. M. Total. Moon rises eclipsed.

Nov. 25 4 21 A. M. 1864 1865 April 10 11 29 P. M. Very small.

4 5 50 P. M. Very small. Oct. 19. 10 27 A. M. 1866 Mar. 30 11 30 P. M. Total. 1867 Mar. 20 3 45 A. M.

Sept. 13 7 30 P. M. 1868 1869 Jan. 27 8 21 P. M.

Aug. 7 6 5 P. M. Total over a southern section 1870

[of the Union. 1871 Jan. 6 4 9P. M. Moon rises partially eclipsed. 1872 ) Nov. 15 0 29 A. M.Very small. 1873 ) May 12 6 23 A. M. Commences 4 h. 34 m. Total in 1874 ) Oct. 25 2 37 A. M. Nearly total. [the W. States. 1875 Sept. 29 6 12 A. M. 1876 Mar. 10 1 5 A. M.

9 Mar. 25 4 45 P. M. Small. 1877 Aug. 23 6 2P. M. Total. Moon rises eclipsed. 1878) Feb. 17 5 58 A. M.

July 29 5 35 P. M.

Aug. 112 7 3 P. M. 1879

Oct.

Year.

Month. D. H. M. A. P. M.

Remarks.

Oct.

1880 Dec. 31 7 42 A. M.
1881 June 12 1 56 A. M. Total.
1882
1883 ) Oct. 16 2 8 A. M.

[the Union. 1884 ) April 10 6 47 A. M. Total in the western parts of

4 5 14 P. M. Visible, and total after the Sun 1885 0 Mar. 16 1 28 P. M.

(sets. Sept. 24 2 56 A. M. [ible in the Western States. 1886 0 Mar. 5 P. M. Commences about sunset. Vis

0 Aug. 29 6 23 A. M. Very small. 1887 Feb. 8 5 4 A. M. 1888 Jan. 28 6 6P. M. Total.

July 23 0 35 A. M. Total. 1889 Jan.

P. M. Penumbra touches WashingJan. 17 0 18/A. M.

[ton about sunset. 1890 1891 Nov. 15 7 36 P. M. 1892 ) May 11 6 0P. M. Visible after sunset.

9 Oct. 20 1 40 P. M. 1893 1894 Sept. 14 11 24 P. M. 1895 ) Mar. 10 10 28 P. M. Total.

Sept. 4 O 49 A. M. Total. 1896 ) Aug. 23 1 55 A. M. 1897 July 29 9 45 A. M. 1898 Jan. 7 7 16 P. M. Small.

D Dec. 27 6 37 P. M. Total. 1899 ) Dec. 16 8 34 P. M. 1900 May 28 8 40 A. M.

« PreviousContinue »