BRITISH ASSOCIATION FOE THE ADVANCEMENT OE SCIENCE. 59 



have continued there till the end of time, notwithstanding any igneous operations 

 which the materials might have afterwards undergone. But as the .'iscovery of 

 very minute traces of phosphoric acid, when mixed with the other ingredients of 

 a rock, is a problem of no small difficulty, an indirect method of ascertaining its 

 presence suggested itself to me in some experiments of the kind which I have insti- 

 tuted, namely, that of sowing some kind of seed, such for instance as barley, in a 

 sample of the pulverized rock, and determining whether the crop obtained yielded 

 more phosphoric acid than was present in the grain, it being evident that any excess 

 must have been derived from the rock from which it drew its nourishment. Should 

 it appear by an extensive induction of particulars, that none of the rocks lying at 

 the base of the Silurian formation, which have come before us, contain more phos- 

 phoric acid than the minute quantity I detected in the slates of Bangor and Llan- 

 berris, which were tested in the above manner, it might perhaps be warrantable 

 hereafter to infer that we had really touched upon those formations, that had been 

 deposited at a time when organic beings were only just beginning to start into 

 existence, and to which therefore, the term Azoic, assigned to these rocks by some 

 of the most eminent of our geologists, might not be inappropriate. The proofs of 

 the former extension of glaciers in the Northern hemisphere, far beyond their 

 actual limits, tend also to complicate the question which has at all times so much 

 engaged the attention of cosmogonists with respect to the ancient temperature of 

 the earth's surface, compelling us to admit that, at least during the latter of its 

 epochs, oscillations of heat and cold must have occurred, to interfere with the pro- 

 gress of refrigeration which was taking place in the crust. On the other hand, facts 

 of an opposite tendency, such as the discovery announced at our last meeting by 

 Capt. Belcher, of the skeleton of an Ichthyosaurus in lat. 71°, and of the trunk of 

 a tree standing in an erect position in lat, 15°, have been multiplying upon us with- 

 in the same period ; inasmuch as they appear to imply, that a much higher tempera- 

 ture in former times pervaded the Arctic regions that can be referred to local causes, 

 and therefore force upon us the admission, that the internal heat of the nucleus of 

 our globe must at one time have influenced in a more marked manner than at pre- 

 sent the temperature of its crust. 



********* 

 Twenty years ago it was thought necessary to explain at our meetings the char- 

 acter and objects of this Association, and to vindicate it from the denunciations ful- 

 minated against it by individuals, and even by parties of men, who held it up as 

 dangerous to religion, and subversive of sound principles in theology. Now so 

 marked is the change in public feeling, that we are solicited by the clergy, no less 

 than by the laity, to hold our meetings within their precincts; and we have never 

 received a heartier welcome than in the city in which we are now assembled, which 

 values itself so especially, and with such good reason, on the extent and excellence 

 of its educational establishments. It begins, indeed, to be generally felt, that am- 

 ongst the faculties of the mind, upon the development of which in youth success 

 in after life mainly depends, there are some which are best improved through the 

 cultivation of the Physical Sciences, and that the rudiments of those sciences are 

 most easily acquired at an early period of life. That power of minute observation 

 — those habits of method and arrangement — that aptitude for patient and laborious 

 inquiry — that tact and sagacity in deducing inferences from evidence short of de- 

 monstration, which the Natural Sciences more particularly promote, are the fruits of 

 early education, and acquired with difficulty at a later period. It is during child- 



