152 Meteoric Astronomy. (April, 
that nearly all the meteor systems encountered by the 
earth travel on orbits largely inclined to the plane of 
the ecliptic, and, therefore, cross that plane in two spots 
(unequally distant in nearly every case from the sun), 
it will be seen how wonderful the circumstance is, that 
some 200 such spots should fall on the fine circle which 
forms the earth’s true track in the ecliptic. 
Fig. 4 is intended to illustrate the remarkable nature of 
this circumstance." Here the circle &,E,E EF, nepresemes 
the earth’s path around the sun, E being the place of the 
earth at the time of the winter solstice. If we suppose the 
width of the circular line E, E,E,E, reduced to about a thirtieth 
part of its present value, we may regard this circle as 
picturing the actual shape of the region traversed by the 
earth. Now we know very little as to the real extent of the 
seventy-six meteoric rings traversed by the earth; but 
the cross section of each (regarded as cylindrical where 
crossing the ecliptic) may average perhaps a million or a 
million and a half of miles. According to the inclination of 
each and the actual direction of motion, the cross section 
with the ecliptic plane will be an ellipse of greater or less 
eccentricity, and having its longer axis in such and sucha 
direction (which may be any whatever), with respect to the 
direction of the earth’s orbit at the place of transit. These 
elliptical sections must, therefore, have some such arrange- 
ment as is depicted in Fig. 4. And it may be noted that for my 
present purpose, it is a matter of no importance whether 
the cross sections of the meteor rings be exaggerated or the 
reverse: since, on the one hand, if the cross sections are 
really larger, the importance of the several meteor zones is 
enhanced, but the circumstance that any given meteor zone 
is encountered by the earth is rendered pro tanto less surpri- 
sing; while, on the other hand, if the cross sections are 
really smaller, we must infer that the number of meteoric 
zones is proportionately greater, to give the earth a reason- 
able chance of encountering so many systems. As to 
the shape of the cross section, it matters little what opinion 
we form; only if the real cross section is circular, the cross 
section on the ecliptic must have different oval shapes 
as shown in Fig. 4. 
So far, then, as the meteoric systems which cross the 
ecliptic descendingly are concerned, we may fairly assume 
that their cross sections on the ecliptic form a scheme some- 
what resembling what is pictured in the figure. It is 
known that southern skies are as plentiful in meteors as 
northern skies, if not more so; hence we must infer that as 
