Royal Astronomical Society* 547 



scopic power, that those who have not been accustomed to study 

 recent sponges with that aid would never recognise a similar struc- 

 ture in the fossils described by him. He also shows that the pre- 

 valence of keratose sponges over those belonging to the genus Hali- 

 chondria is what might naturally be expected, as the spicula which 

 form the skeleton of the latter would be less likely to be preserved 

 in their original position than the horny fibres of the former. 



Lastly, the author alludes to the great share which sponges have 

 had in the production of the solid strata of the earth's crust. 



ROYAL ASTRONOMICAL SOCIETY. 

 [Continued from p. 327-] 



January 8, 1841. — Remarks on the Present State of our Know- 

 ledge relative to Shooting-Stars, and on the Determination of Dif- 

 ferences of Longitude from Observations of those Meteors. By Mr. 

 Galloway. 



After adverting to some of the earlier opinions which have been 

 entertained on the nature of fire-balls, shooting-stars, and other ig- 

 neous meteors, the author remarks that no very definite theory was 

 formed respecting them till towards the end of the last century ; 

 for although the cosmical origin of the more remarkable bolides 

 and fire-balls had been suspected, the shooting- stars were generally 

 regarded as atmospherical phenomena, which were ascribed by some 

 to electricity, and by others to the inflammation of hydrogen gas 

 accumulated in the higher regions of the atmosphere. In 1794, 

 Chladni published his celebrated work, in which he gaVe a catalogue 

 of all the. recorded observations of fire-balls ; and, from a comparison 

 of the different descriptions, inferred that these meteors have not 

 their origin in our atmosphere, but are cosmical masses moving 

 through the planetary spaces with velocities equal to those of the 

 planets, which, when they encounter the earth's atmosphere, are in- 

 flamed by the resistance and friction, and become luminous, some- 

 times bursting into pieces, and scattering masses of stone and iron 

 on the ground. This opinion was at first greatly ridiculed ; but 

 the repeated and even not unfrequent fall of meteoric stones, and the 

 discovery by Howard that all of them present an almost perfect si- 

 milarity of constitution, widely different from that of any substance 

 found on the earth, at length forced conviction even on the most 

 sceptical. From the close resemblance between fire-balls and shoot- 

 ing-stars, and, indeed, the impossibility in many cases of distinguish- 

 ing the one class of meteors from the other, Chladni was led also to 

 ascribe a cosmical origin to the latter phenomena. At this period, 

 however, there were no observations from which precise or certain 

 conclusions could be formed respecting the altitudes, velocities, or 

 paths described by the shooting- stars — the elements by which the 

 question of their existence within or beyond the atmosphere could 

 be solved. In the year 1798, the first series of observations for de- 

 termining these points was undertaken in Germany by Brandes and 

 Benzenberg. Having selected a base-line of about nine English 



