OBSERVATIONS OF LUMINOUS METEORS. yas 
on Large Meteors and Aérolites, yet the careful investigation of its real path 
and of its orbit round the sun made by Dr. Galle and by other German 
astronomers, from the many exact observations that were obtained in their 
neighbourhood of its appearance, render its description in the first place of 
this Appendix especially appropriate. The meteor was seen in full twilight 
at 8" 46™ p.at., Breslau mean time, about half an hour after sunset, skirting 
the 8.W. horizon at no great altitude at Breslau, and proceeding with very 
little downward inclination westwards : by means of a meteoroscope Dr. Galle, 
who saw the meteor at Breslau, obtained the exact places of two points on 
the luminous streak which it left visible in the sky for more than a quarter 
of an hour after the disappearance of the nucleus; and an assistant at the 
Observatory, who also saw it, accustomed to observe the time of flight of 
ordinary shooting-stars, counted 9 seconds as the duration of the meteor’s 
flight from its first appearance until the time of its explosion and extinction. 
Dr. Weiss at Vienna, and Dr. Hornstein at Prague, communicated to Dr. 
Galle equally valuable observations. In the pages of the ‘ Astronomische 
Nachrichten’ (No. 1955) for September 1873, an exact calculation of the 
meteor’s real path by Prof. vy. Niessl, of Briinn, from ten or twelve excel- 
lent descriptions of its course at places in Moravia and Bohemia (imme- 
diately beneath or on the west side of the meteor’s course), had appeared. 
Dr. Galle observes that but for the unusual astronomical exactness of some 
accounts, the particulars of which had reached him from Silesia and places 
chiefly east of the meteor’s course, it would have been superfluous to recalcu- 
late the meteor’s course by the new rigorous method which he proposed from 
all the observed data, so perfectly did the observations collected, and the cal- 
culations made from them by Prof. y. Niessl, establish the general character 
of the meteor’s course. Complete mathematical formule are given by Dr. 
Galle, showing how, independent weights having first been assigned to the 
positions given in the different observers’ descriptions, the whole can be 
combined together so as to furnish without very laborious calculation the 
most probable path, and the amount of probable error of the determination 
of the meteor’s real course. Apart from these calculations, Dr. Galle also 
visited the locality in Oberlausitz, between Saxony and Bohemia, over which 
the meteor appears to have exploded, and ascertained the correctness of this 
supposition from the accounts of many observers who saw the meteor burst 
there directly overhead. It has been conjectured by Dr. Galle, in his in- 
vestigation of the real path of the fireball and other interesting questions 
relating to the shower of stones at Pultusk, near Warsaw, on the 30th of 
January, 1868 (see the volume of these Reports for 1868, p. 388), that the 
so-called bursting into fragments, or “ explosion,” and the accompanying loud 
reports seen and heard at the disappearance of large detonating or aérolitic 
fireballs, arise from the expansion of compressed air before the meteorites at 
the moment when their once planetary velocity is so arrested and diminished 
by resistance as to allow soutid-waves to start from them in all directions ; at 
that time the intense illumination ceases and the largest fragments only pur- 
sue their onward course, also shortly to become extinguished and to produce 
louder and more violent reports than the smaller stones, from their greater 
surface and exposure to compression of the air. Thus as each atom, grain, 
or fragment of a stone-swarm, when it first enters the atmosphere, is 
arrested in its flight, it yields up its light and planetary speed, and following 
as a dull spark in the meteor’s train, it marks the first moment of its fall 
towards the earth under the mere influence of gravity alone by a more or less 
audible explosion. To observers near the point of disappearance of such 
large meteors, the loudest explosions arising from the largest aérolites which 
