1864. J 399 [Chase. 



This table shows — 



1. That the average of the three years corresponds precisely/ wiih 

 the theory, except in the secondary maximum, which was one day- 

 late. 



2. That the primary maximum occurred at the quadratures in 1845 

 and 1846, and one day before the quadratures in 1844. 



3. That the primary minimum occurred at the .syzygies in 1844 

 and 1S45, and one day after the syzygies in 184G. 



4. That 1846 was a disturbed year; and, if it were omitted from 

 the table, each of the remaining years, as well as the average, would 

 exhibit an entire correspondence with theory, except in the primary 

 maximum of 1844. 



5. That 1845 was a normal year, the primary and secondary 

 maxima and minima all corresponding with tlreory, both in position 

 and relative value. 



6. That the deviations from perfect correspondence with theory 

 can be easily explained by the relative positions of the two aerial 

 ellipsoids of rotation and attraction. 



7. That the tertiary maxima and minima, or the turning-points 

 between the primary and secondary maxima and minima, are less 

 stable than the primaries and secondaries. 



At extra-tropical stations I should look for important modifications 

 of the theoretical results, some of which I propose to explain in a 

 future communication. 



Mr. Lesley Jrew tlie attention of the members to the re- 

 searches of M. Delesse on the quantity of " water of imbibi- 

 tion" and "water of the quarry" contained in rocks, pub- 

 lished in the Bulletin of the Geological Society of France 

 (2e ser. t. xix, p, 64, seance du 4 Nov., 1861), as having an 

 important bearing on the ancient changes of sea-level. 



The tables of M. Delesse, given on pp. 66, 69, 72, go to show 

 that dry specimens of gypsum, limestone, chalk, slate, sandstone, 

 gneiss, granite, &c., can be made to imbibe an amount of water 

 equal to from 1 per cent, to 40 per cent, of their weight; and that 

 in their natural places they hold from 1 per cent, to 30 per cent, of 

 water permanently; granite holding 15 per cent. ; argillaceous rocks 

 20 per cent, or more ; and the magnesian rocks a still larger per- 

 centage. The whole exterior of the crust of the earth is bathed in 



