MARINE BIOLOGICAL STATION AT PORT ERIN. 5e 
-Murray’s friend, Dr. Johan Hjort. At Murray’s request this 
vessel was lent, with her crew and equipment, by the Norwegian 
Government for the North Atlantic cruise, Sir John Murray 
undertaking to pay all the expenses. The scientific reports 
on the Expedition will be published im a series of volumes by 
‘the Bergen Museum; but the more general results have 
appeared in popular form in a volume entitled, ““ The Depths 
of the Ocean” (Macmillan, 1912), by Murray and Hjort, with 
_ contributions by several other naturalists, which gives a con- 
densed account of the modern science of Oceanography, with 
special chapters on the latest discoveries, based largely upon 
_ the experiences of this North Atlantic cruise taken along with 
_the previous cruises of the “ Michael Sars” in the Norwegian Seas. 
4 Amongst noteworthy matters that are discussed in this 
_ yolume we find :— 
(1) Methods of plankton collecting, including the towing 
_of.as many as 10 large horizontal nets, at various depths, 
simultaneously. The pelagic plants collected, either in the 
nets or by centrifuging the water, are discussed in a notable 
- chapter by Gran. 
4 (2) The “ Mud-line,”’ a favourite subject with Murray, as 
being the great feeding-ground of the ocean. He places it at an 
_ average depth of 100 fathoms, on the edge of the ‘‘ Continental- 
shelf,” at the top of the “ Continental-slope,’ which descends 
more or less precipitately to the floor of the Atlantic at an 
] average depth of 2,000 fathoms. We know from Murray’s 
_ careful estimations that, if all the elevations of the globe were 
‘filled into the depressions, we should have a smooth sphere 
covered by an ocean 1,450 fathoms deep. The floor of this 
ocean is the “ mean sphere level.”’ 
(3) Dr. Helland-Hansen, the physicist on board the 
“Michael Sars,” had devised a new form of photometer, 
which registered light as far down as 500 fms. in the Sargasso 
Sea. At between 800 and 900 fms., however, no trace of light 
