ASTRONOMICAL.

Thames Star, Volume VIII, Issue 2895, 27 May 1878, Page 4

ASTRONOMICAL.

On Monday night Professor Ball, the Astronomer Royal for Ireland, gave a lecture at the London Institution, on "Recent additions to .our knowledge of „ Shooting Stars." The lecturer reminded his hearers that besides the stars we see on a clear night, and besides those the telescope mates known, there are countless bodies moving through space, which even the most powerful telescope fails to reveal, till they come either in the orbit of the earth or of its atmosphere. These are what are called meteorites and t shooting stars, and it is important to distinguish clearly between the two. ■.t They are alike luminous from the same cause, that of friction in passing through the atmosphere, though but few people have ever seen a meteorite falling. The number of shooting stars is infinitely greater than is usually supposed, for observers with telescopes often Bee them flash across the field in dimen-, lions, too small to be seen with the naked eye. We know that ahootiDg stars undergo combustion in passing through our atmosphere. What becomes of the debris P The snow of the Alps, far away from furnaces, contains globules of iron, and dust that has quietly accumulated in exposed places contains them also. It is supposed they represent some of the debris. Though we^ may , grumble,at our atmosphere in bad weather, ■we must recollect.it, at least, does this, it

burns up these bodies that are pelting „ down upon us at a rate 100 times greater than the missile of an 81-ton gun, and, but for this burning up, they would be at any rate awkward for us. In looking at the knowledge accumulated with regard to shooting stars, the first point to notice, Professor Ball says, is that certain great Bhowers are periodical, and always come from the same parts- of the heavens. , According to the constellation from which tbey appear to come, they are called Lyraids, Pergeids, Orionids, Leonids, &c.

The inference from these recurring periods is that the orbit of the earth then cuts the orbit in which a mass of these is moving. With this fact of recurrence it must be noticed tbat certain comets are

periodical, and from, a comparison of their :; supposed orbits with those of groups of these bodies, a connexion between them is inferred, whatever may be the origin of the comets, which is not yet known. Meteorites,, on the contrary, are never known to come from the direction of a , comet path. If a meteorite is carefully examined, it is seen to be a fragment of Borne rock,sl|ttj||tbat of one closely analagous to (^pf earth's volcanic rocks. If we consider Jih^turn the volcanic sources from which - they could have" come, we see the sun would have force enough to drive off fragments; but it is hardly likely that there are solid rocks there lo drive off. Jules Verne is .right, Professor"Ball says, in calculating .that a body driven up from the earth with a force equal to six'miles a second would 'not return. From Ceres three miles a

second would be sufficient. Examining

all the planets in turn, it seems improb- ~ able that the meteorites originate from -any of them. It seems very much more ■likely that they were in former times of ■greater volcanic activity driven up from the earth itself, and they again after lapse of ages meet the earth in its orbit.' The theory that they come in from unlimited space, is, Professor Ball thinks, highly improbable.—Times, Feb. 15.