568 Proceedings of the Royal Society 
It is doubtful whether an area of any great extent, of above 50° 
of range, is to be found in Northern Africa, though one observation 
w r ould seem to show that such does exist. The observed range at 
Biskra, in the interior of Algeria, is 54° ; but since the observa- 
tions at that station have not been made for any considerable 
period, no weight has been given to their indication. We find the 
line of 50° range entering Europe at the north of Norway, passing 
south to the centre of the Peninsula, then turning east to the coast 
at Hernosand, bent north by the Gulf of Bothnia to Carlo or the 
Finland coast, then turning south inland to near the Gulf of 
Finland, and again carried northward by the influence of the 
great Russian lakes ; thence it passes southward midway between 
Moscow and St Petersburg to near the north-west side of the Black 
Sea, where it turns sharply to the eastward above the Black Sea 
and the Sea of Azov, and along the northern side of the ridge of 
the Caucasus to the Caspian. Round this sea the line of 50° range 
forms a loop which passes through the north-western part of the 
sea, but close to the remaining coasts, back to the south slope of 
the Caucasus; thence it passes westward through Erzerum into 
the interior of Asia Minor, curves round, and reversing its course, 
turns back into Asia through Persia, Tibet, and China to the 
eastern coast in the Yellow Sea, through the Corea, Saghalien 
Island, and Kamtchatka to the American coast at the mouth of 
the Kwichpak River in Alaska ; thence southward into the interior 
of the continent to beyond the Great Salt Lake, where it turns to 
the east with two curious bends, and is carried to the north round 
the coasts of the great American lakes, only cutting off the north- 
west coast of Lake Superior with a greater range. It is curious to 
observe that the three greatest inland sea and lake regions in the 
northern hemisphere, the lakes of European Russia, the Caspian Sea, 
and the American lakes, have the same range of temperature ; and 
that Fort-William, on the north-west coast of Lake Superior, has 
exactly the same range of 58°, observed at Astrakhan in the same 
relative position to the Caspian. From the Canadian side of the 
lakes near Ottawa, the line of 50° range bends south into the 
United States to as far as Albany in New York, then north-eastward 
through New Brunswick to the coast of Labrador, where three 
stations have this range. Keeping still northwards, it passes 
