21 



copies of which may be hacl of the Secretary. The nucleus of a 

 good scientific Hbrary for the use of members has been formed, and 

 contains already some valuable works. The number of members 

 is 99, and the balance sheet shows eight pounds in favour of the 

 society. Next came the election of a President, Dr. FitzGerald 

 having resigned at the previous annual meeting and no one having 

 been appointed in his place. He was present in the chair, however 

 that evening, and proposed as his successor Dr. Thomas Eastes, 

 whose name was warmly received and who was unanimously elected. 

 The same Vice-Presidents as before were chosen, and also the 

 committee, to which latter were added the names of Mr. Hambridge, 

 Mr. S. Hilla, and Mr. A. H. Ullyett. Mr. Kerr remains Secretary 

 of the microscopical section, and Mr. H. Ullyett, General Secretary. 

 Business matters were succeeded by the second part of Mr. H. 

 Ullyett's lecture on the Ice Age, illustrated by lantern slides. After 

 giving a brief descriptiou of ice and ice phenomenas as at present 

 displayed in Greenland, India, and Switzerland, he proceeded 

 to give the generally accepted 



CAUSES OF AN ICE AGE. 



About the causes of these glacial periods there have been many 

 theories, e.g. : (a) That the solar system, in its journey as a whole 

 through space, passes through regions of varying temperatures ; 

 (b) That the hot and cold ages are caused by the changes of position 

 in the earth's axis ; (c) By varying elevations of the continents and 

 by change of positions of land and sea ; {d) The astronomical 

 explanation connected with the name of Dr. CroU, and more fully 

 worked out lately by Sir Robert Ball. 



It would be impossible for us this evening to enter fully into all 

 these theories and to point out their probability or improbability. I 

 shall therefore confine what little I have to say to the last, the 

 astronomical theory, so extensively held at the present time, 

 although many good authorities are beginning to fall back on some 

 of the others, notably the varying elevation of the land. 



To make this theory of Dr. Croll's perfectly clear, it is necessary 

 to enter to a slight extent upon the astronomical relations of the 

 earth. The path described by the earth in its yearly journey round 

 the sun is called its orbit; the path which the snU; in consequence 

 of the earth's movement appears to describe, is called the eliptic. 

 It is important, in connection with our explanation, to bear in mind 

 that the earth's orbit is not a circle, although it does not differ 

 much from that figure. It is actually an ellipse of small eccentri- 

 city, by no means the exaggerated ellipse which is often so mis- 



