24 JOURNAL AND PROCEEDINGS 
SYNOPSIS OF PAPER ON ‘‘ECLIPSES’’ 
Read before the Hamilton Association, December 13, 1904, by 
PROF. DeLURY, OF TORONTO. 
By the use of a series of well executed diagrams the speak- 
er showed clearly why the obscuring of the sun and moon did 
not occur as frequently as their constant and uniformly regular 
motions might naturally lead us to expect. é 
The inclination of the moon’s orbit to the plane of that of 
the earth partly accounts for this. 
The path of the moon intersects the apparent path of thesun 
at an angle of about 5 degrees, thus preventing them from being 
in true alignment with the earth except at these points of inter- 
section. 
But owing to the acuteness of the angle with which these 
lines cut each other, eclipses of greater or less magnitude may 
occur according as the moon is in a position of relative proxim- 
ity to these nodal points. 
Beyond a comparatively limited range of are, however, it is 
plain that the diameter of the moon is not sufficient to throw us 
a shadow and obscure our view of the sun and there can be no 
eclipse visible to us at least until the moon approaches the 
next node. 
Hach succeeding pair of related nodes does not have the same 
position as the preceding ones, but they seem to follow the line 
of a curve marked out by these constantly recurring points of in- 
tersection of the orbit of the moon and the apparent path of 
the sun. 
This curve seenis to make a complete circuit in something 
lke 18 years and some 10 or 11 days. 
This complete round of retrogression of the moon’s nodes con- 
stitutes a cycle of eclipse, and therefore the eclipses occurring 
during one such period may be expected to be repeated in the 
