EDITOEIAL NOTES. 
One of the most important subjects brought into prominence by the contribu- 
tions of the Challenger Expedition to the Science of Oceanography was that 
of Oceanic Circulation. It is possible to observe directly the rate and direc- 
tion of the surface currents of the ocean, and, by means of current drags and 
other instruments, to gather some information with regard to the motion and 
direction of undercurrents at no great distance beneath the surface in some 
parts of the ocean, such as, for instance, the Strait of Gibraltar and the Bos- 
phorus. In the greater depths of the ocean the motion of the water is too 
slow for observations of this nature, and it becomes necessary to trace move- 
ments by a study of the temperature and specific gravity of the ocean waters. 
As the examination of the Challenger observations bearing on the question 
of oceanic circulation proceeded, it became apparent that a full discussion 
of atmospheric circulation was required as a necessary preliminary. Accord- 
ingly I induced Dr. Alexander Buchan to undertake the preparation of a 
Report on Atmospheric Circulation based on the Challenger and other avail- 
able meteorological observations, and a Memoir on this subject was published 
five years ago. Shortly afterwards Dr. Buchan commenced the discussion of 
the data bearing on oceanic circulation, the most important of these being 
the Challenger observations. All other published data obtainable has been 
made use of in the discussion, and, in addition, a large amount of unpublished 
data was placed at Dr. Buchan’s service by the Meteorological Council and 
by Admiral Wharton, Hydrographer of the Admiralty. The prejDaration of 
this Memoir has occupied the whole of the time at Dr. Buchan’s disposal 
