Geological Society, 237 



been employed, and monthly observations have been made with it, 

 generally in the afternoon — two needles being used, as before. 

 From this circle we have the following results : — 



Year. Mean dip. Yearly secular change. 



1860. 



68 20-21 



i 



1861. 



18-21 



2-00 



1862. 



15-58 



2-63 



1863. 



12-66 



2-92 



1864. 



9-88 



2-78 



exhibiting between 1860 and 1864 a mean secular change of 2'-58. 



It will be noticed from this, that the mean yearly secular change 

 of dip at Kew appears to be greater from 1860 to 1864, a period of 

 increasing disturbances, than from 1854 to 1859, a period of decrea- 

 sing disturbances. Possibly the yearly decrement of dip has again 

 begun to diminish, since the change from 1864 to 1865 is only l'*32. 

 It is, however, premature to assert that this is the case, and it can 

 only be decided by continuing the monthly observations. At all 

 events the Kew observations agree with those at Toronto in indica- 

 ting that the yearly change of dip contains the combined result of 

 two things — namely, the true secular change and the change due to 

 disturbance ; and this ought to be borne in mind by future observers 

 of this magnetic element. 



GEOLOGICAL SOCIETY. 



[Continued from p. 160.] 



January 24, 1866. — W. J. Hamilton, Esq., President, in the Chair. 



The following communication was read : — 

 " Notes on Belgian Geology." By R. A. C. Godwin- Austen, 

 Esq., F.R.S., For. Sec. G.S. 



This communication related to the Upper and Lower Kainozoic 

 formations of Belgium, in the following order: — 1. The Polders, 

 or sea-mud beds, and their equivalents. 2. The Campine sands, 

 and Los, or Limon de Herbaye. 3. The Boulder formation. 4. Cail- 

 loux Ardennais. 5. The Lower Kainozoic, or Crag. 



The Polders, which form a belt along the sea-board of Belgium and 

 Holland, occasionally running inland up the courses of rivers, as up 

 the Scheldt to Antwerp, indicate an elevation of very small amount, 

 corresponding to the raised estuarine and other beds around our own 

 coasts. They are covered by dunes and drifted sands. A great 

 deal of the fen-land at higher levels, w T ith peat and bog-iron, belongs 

 to the age of the Polders, and of still earlier times, inasmuch as the 

 Polders very generally overlie a terrestrial surface. The Campine 

 sands, which run parallel with the coast from North Holland to- 



