220 Proceedings of Learned Societies. 



i 

 Switzerland. In addition to these circumstances, it is highly pro- 

 bable that, during the icy period, the Gulf stream, at present so 

 great a source of heat, did not visit our shores, but, owing to the 

 different shape of North America, took an altogether different direc- 

 tion. The very imperfect state of our knowledge has given us as 

 yet no proof of the existence of man during this period of extreme 

 cold ; though it has been ascertained that he flourished in Europe 

 during an early part of the post-glacial period. Early education 

 and tradition make it difficult for us to allow the long periods of 

 time that must be granted for the changes which have taken place 

 in the earth's surface. The geologic record is very fragmentary ; 

 and the more that is known of it, the more this fact is realized. In 

 the lowest half of the series of Laurentian rocks, Dr. Dawson, of 

 Montreal, has detected, by the aid of the microscope, the distinct 

 structure of a large species of Rhizopod. The rocks in which this 

 fossil — called the \E0z001i Ganadense — have been found, are as old, if 

 not older, than any of the formations termed Azoic in Europe. 

 Specimens have been brought to England by Sir William Logan, 

 and are exhibited at the Association. 



Thursday, September 15/7?. — In the section of Mathematical and 

 Physical Science, Mr. Glaisher read a paper on Luminous Meteors. 

 He said that numerous observations of fire-balls had been made. 

 The largest had been seen on the night of the 5th December, 1863, 

 and had produced a vivid impression of lightning over the whole of the 

 British Isles. Eire-balls and shooting-stars are supposed to be 

 loosely compacted, and in this way their want of penetrating power 

 may be accounted for. Shooting-stars commence at 70 miles, and 

 disappear at 50 miles above the surface of the earth. The meteors 

 observed on the 9th and 10th of August, 1804, were in numbers 

 nearly about the average of the phenomenon — namely, between 30 

 and 40 meteors per hour, for a single observer constantly regarding 

 the sky near the zenith. They were not half so many in number as 

 they were in 1863 on the corresponding dates. If any indication of 

 periodicity can yet be traced in the fluctuations of this phenomenon, 

 it is, perhaps, a minimum at intervals of eight years, which has 

 thrice occurred, and on the last occasion in 1862. 



Professor Hennessey read a paper on the Ellipticitt of Mars. 

 He said that the physical characters of the planet Mars have always 

 been interesting on account of its supposed likeness in form to our 

 own earth. In accordance with hydrostatical laws, a planet similar 

 to Mars, and rotatory round its own axis in the same period of time, 

 should have an ellipticity very nearly approaching that of our earth. 

 Bessel and Johnson, observers of eminence, appear to have arrived 

 at this conclusion, though some consider that the ellipticity of Mars 

 is much greater. It is generally admitted that, in the neighbour- 

 hood of one of the poles of Mars, there exists a great mass of 

 brilliant matter, analogous to a mass of terrestrial snow. This 

 substance, if it is snow, must be situated on masses of land near tlio 

 poles of rotation, and must vary in dimension as the seasons of the 



