The fact that the position of the radiant point does not change with the earth's rotation, places the cosmical origin of the meteors wholly beyond question. The theory of a closed ring of nebulous matter revolving round the sun in an elliptical orbit which intersects that of the earth, affords a simple and satisfactory explanation of the phenomena. This theory was adopted by Humboldt, Arago, and others, shortly after the occurrence of the meteoric shower of 1833. That the body which furnishes the material of these meteors moves in a closed or elliptical orbit is evident from the periodicity of the shower. It is also manifest from the partial recurrence of the phenomenon from year to year, that the matter is diffused around the orbit; while the extraordinary falls of 1833, 1799, 1366, and 1202, prove the diffusion to be far from uniform. ELEMENTS OF THE ORBIT. Future observations, it may be hoped, will ultimately lead to an accurate determination of the elements of this ring: many years, however, will probably elapse before all the circumstances of its motion can be satisfactorily known. Professor Newton, of Yale College, has led the way in an able discussion of the observations.[6] He has shown that the different parts of the ring are, in all probability, of very unequal density; that the motion is retrograde; and that the time, during which the meteors complete a revolution about the sun, must be limited to one of five accurately determined periods, viz.: 180·05 days, 185·54 days, 354·62 days, 376·5 days, or 33·25 years. He makes the inclination of the ring to the ecliptic about 17°. The five periods specified, he remarks, "are not all equally probable. Some of the members of the group which visited us last November [1863] gave us the means of locating approximately the central point of the region from which the paths diverge. Mr. G. A. Nolen has, by graphical processes specially devised for the purpose, found its longitude to be 142°, and its latitude 8° 30´. This longitude is very nearly that of the point in the ecliptic toward which the earth is moving. Hence the point from which the absolute motion of the bodies is directed (being in a great circle through the other two points) has the same longitude. The absolute motion of each meteor, then, is directed very nearly at right angles to a line from it to the sun, the deviation being probably not more than two or three degrees.