198 KANSAS CITY REVIEW OF SCIENCE. 
or three in a month's time, then no more for nearly half a year. More than three 
can never occur at the same node ; and it takes nearly six months for the Sun 
to pass half round — from one node to the other. Thus there are always two 
eclipse seasons in a year; and when one occurs near the first of January a third 
one sets in near the close of December. It will also be noticed that they return 
about twenty days earlier each year — caused by the nodes falling back on the 
ecliptic — being in April and October in 1800; and mostly in January and July in 
1805. So in eighteen years and eleven days they go through the full circle of 
the ecliptic and return to April and October; but ten or eleven days later in the 
months. Here we see an indication of the Saros, the use and appHcation of 
which were described in the Review for March, 1882. You may take either of 
the eclipses of 1800 and find that it jecurred every eighteen years and ten or 
eleven days through the century, excepting the lunar eclipse of October 2d, which 
disappeared, or wore off, in 1872, November 14th. 
The eclipse of 1835, June loth, was the first one of a new series. So was 
that of July 28, 1870. A series of solar eclipses "wore off" in 1859, Feb- 
uary 2d, near South Pole (being at the "A. N.") The eclipse of 1890, June 
3d, is the last of that series — until it comes round again in about 13,000 years. 
Thus a set of eclipses begins, or one ends, on an average of about every Saros. 
The size or magnitude, given in the table, is the largest that the eclipse appears 
anywhere on the earth. A central eclipse of the Sun with its partial eclipse each 
side of the Central Line extends over a belt of the world 4,000 to 5,000 miles 
wide, and about 10,000 miles long — bearing northeasterly when it occurs at the 
A. N., and southeasterly when at the D. N. When two places are named in the 
column " where visible," for the Sun they indicate, approximately, the beginning 
and end of the Central Line ; and for the Moon, the middle meridian of the hem- 
isphere in which it is visible. 
It may be observed that no United States jmr of the century produced seven 
eclipses. But an eclipse of the Sun occurred 1804, December 31, 8 P. M., 
which was January ist, i A. M., 1805, in England. Now, there were six 
eclipses after this one in that year — making seven eclipses (the greatest number 
that can ever be in one year) in 1805 in the eastern hemisphere; but only six in 
the same year of western hemisphere time. There were nearly seven eclipses in 
1823 — the last one occurring about four hours after New Year's day, 1824, Wash- 
ington time. But about five hours, or 75°, west of Washington, it was still 1823 
when the eclipse took place. So there was a narrow belt of Central Pacific — 
probably including Sandwich and Society Islands — where seven eclipses occurred 
in its year 1823. In the first fifty years of the century there were 199 eclipses ^ 
and 196 in the last fifty years — 395 in all. 
