THE PERSEID METEORS.—This well-known shower of meteors should be of the greatest interest to the mathematician, as well as to the observer. At Pulkova, in 1893, the shower was observed from July 22 to September 12, and a discussion of the 563 paths recorded forms the subject of an interesting paper by Dr. Bredichin (Bull. Imp, Acad. Sc., St. Petersburg, September 1894). It has long been known that the Perseids are not as other regularly recurring meteor showers, and Dr. Bredichin explains their peculiarities by supposing that they are not produced by a swarm of meteorites, in the true sense of the word, but by particles circulating in different orbits. These orbits have widely differing inclinations, and the other elements also show striking departures from each other. One gets a good idea of the system which is suggested, by imagining a bundle of materialised orbits crossing the earth's orbit at the points which the earth occupies during August, and for some days before and after. The particles with long periods correspond to the meteors at the beginning of the showers, and to the primitive position of the comet from which the meteors are supposed to be derived, which, having a moderate period, has left these meteors behind. The position of the node of the comet is not symmetrical with reference to the nodes of the meteors, but appears to be nearer the beginning than the end of the showers. This continuity of the phenomena for so long a time seems to confirm the idea of a variety of periods for the particles, and indicate also the repeated omission of the meteors from the body of the comet. If the forces of disruption were only those which have ordinarily been considered, the meteors would be dispersed in a long thin stream along the length of the orbit, as in the case of the November meteors; but since the orbits of the meteors are variously inclined to that of the comet, another force, acting transversely to the plane of the orbit, must be admitted as an important factor. The anomalous phenomena of the tails of some comets-7-a subject with which Dr. Bredichin is already closely associated -and the energetic emissions which have been noted in several comets, including that which is connected with the Perseids, serve to demonstrate the possibility of such an action as that which he supposes to have taken place in the case of this swarm.