ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxxix 



deeper as geological time advanced and the earth gradually parted 

 with its heat by radiation into surrounding space. 



Under this view there would be a tendency over the face of the 

 globe to retain a general crust upon it of a thickness increasing with 

 the lapse of geological time, less uneven beneath as a whole than 

 above from the kind of action to which it would be subjected, and 

 yet no part protruding so far as to cause any very material difference 

 in the figure of the earth or of density in the parts of such crust, 

 viewing the subject on the large scale. It would not appear im- 

 probable, that notwithstanding the dislocation, unequal tilting, and 

 squeezing together of masses, the adjustments were such as to keep 

 a spheroidal coating of the mass beneath which did not very mate- 

 rially differ as a whole in density. Should this not have been so, we 

 have in our geological hypotheses to take into account the effects 

 pointed out by Sir John Lubbock as resulting from the modification 

 or absence of the general conditions above inferred, their amount 

 or geological value necessarily depending upon the magnitude of the 

 causes to which he adverts. 



Such have been the labours of our Society during the past year. 

 They embrace most varied subjects, all tending to the advance of our 

 science, and certainly showing no decrease in the zeal of our members 

 or in the importance of the matter brought before us. The discus- 

 sions which have arisen upon the communications have been cha- 

 racterized by the same kind feeling and love of truth, for its own 

 sake, as heretofore, and we may congratulate ourselves with the cer- 

 tainty that the energies of our body are unimpaired, that the feeling 

 of brotherhood is as strong among us as ever, and that the Society 

 never was in a more efficient condition for the promotion of the branch 

 of knowledge we cultivate than at this our forty-first anniversary. 



Other Geological Societies of the United Kingdom. 



While we have been thus engaged, the other geological societies of 

 our country have also been occupied with their duties during the past 

 year. 



The Geological Society of Dublin has continued to aid the pro- 

 gress of geology, though its meetings, now held at Trinity College, 

 Dublin, were suspended in May and June, from the occupation, in 

 part, of that college by troops in consequence of the disturbed state 

 of Dublin at that time. There were two communications from Mr. 

 Mallet. The first on molecular changes observed in the structure of 

 recent shells. He found that in some recent oyster-shells, imbedded 

 at about tide-level in red and grey marl cliffs, occurring on the north 

 of Belfast Lough and eastward of Carrickfergus, the cavities between 

 the nacreous plates were in progress of being filled up by calcareous 

 spar, in rhombs, whose minor axes were perpendicular, or nearly so, 

 to the plates of the shell. When this filling-up had been nearly per- 

 fected, the whole substance of the shell had undergone a change of 

 molecular structure, and in place of the parallel plates presenting the 

 usual character under the microscope they were obliterated, and the 

 whole substance of the shell had assumed the crystalline form of cal- 



