1872.] Meteoric Astronomy. 153 
many cross sections as are depicted in Fig. 4 should be 
added (all overlapping the circle E,E,E£,E,) to represent the 
meteor systems which cross the ecliptic ascendingly, or from 
south to north. Moreover, an addition should be made for 
meteor systems which have hitherto escaped notice, as well 
as for a considerable number (perhaps nearly as many again 
as all yet mentioned) which, because they strike the earth’s 
course on its inner or sun-illumined side, fall on the earth 
where day is in progress, and so escape recognition alto- 
gether. Add also the more sparse systems of ‘“‘ heavier 
metal” which produce fire-balls, and those others which 
have supplied the countless myriads of aérolites which are 
known to have fallen on the earth. I think it will be 
granted, that if all these circumstances were taken into 
acccount in Fig. 4, the earth’s orbit, as there pictured, 
would be absolutely encumbered with the oval spots repre- 
senting the cross sections of meteoric systems. 
Now let it be remembered that each of the cross sections 
corresponds to a long stream of meteors, if not to a 
complete zone, the meteors travelling around orbits com- 
pared with which the orbit E,E,2,E, has utterly insignifi- 
cant proportions. Imagine the seventy-six cross sections of 
Fig. 4 replaced by seventy-six curves carried on various 
arcs, even only across the circular space E,E,E,E, (that is, 
leaving out of account altogether those portions of the 
systems which lhe farther away from the sun). Conceive 
the like done for about twice as many more systems corre- 
sponding to the orders just mentioned. ‘This considered, it 
will surely begin to appear that the sphere of space around 
the sun, which E,E,E,E, will represent, is occupied in a 
remarkable manner by interlacing meteor-comet systems. 
But it is certain that the earth’s orbit is not clustered 
round with meteoric cross sections in the peculiar manner 
depicted in Fig. 4. That all those cross sections are there 
cannot be questioned, since so many northern meteor 
systems have been recognised. But outside and inside 
E,E,E,E, there must be meteor cross sections which the 
earth does not traverse. To suppose otherwise is as though 
a person who had traversed a certain route in a rain storm, 
should suppose that no rain had fallen to right or to left of 
his track. There is nothing in the earth’s orbit to attract 
meteors. She herself has not the attractive energy neces- 
sary either to compel meteors to approach her track or to 
retain them against other attractive influences. It is only by 
chance, as it were, that her track hes thus through those 
special hundreds of meteor systems,—precisely as it is only 
VOLE. 11. (N7S.) X 
