603 
1908-9.] Observations on Deep Water Oscillations. 
two water-layers (the surface water and the deep water) in the same part 
of the ocean. Likewise, the idea of tidal waves of so long periodicity as 
those described in the annexed diagram existing in such a limited part of the 
ocean as Skagerak presents almost insurmountable difficulties, whether they 
are assumed to have the character of forced or free waves. On the contrary 
Fig. l. 
The contours show depths every 50 fathoms. 
the whole character of the phenomenon bears out the idea that it is essenti- 
ally an oscillation in the deep water of the ocean, the origin of which must 
be left to future investigation to discover.” 
The observations of the Scottish Lake Survey have shown the presence 
of oscillations in the lower water of deep lakes during the autumn of the 
year, when there is a layer of warm water of uniform temperature super- 
imposed on the colder abysmal waters. When the boundary between the 
