84 
MR. II. X. DICKSOX OX THE CTRCULATIOX OF THE 
is one of the most important features of this chart, being a complete change, at least 
for the latter, since the previous month, and representing an increase of salinity over 
a wide Ijelt just south of lat. G0° N. The westward-jDointing tongue formed by these 
lines is continued into Davis Strait hv the 34'5 and 34’0 lines. 
c/ 
Apart from the increased information afforded by this majj, the most im23ortant 
features are—marked steejDening of gradients, both of temperature and salinity, on the 
American side ; extension of the cold mid fresh area south-eastward, between long. 40° 
and 50° W. : absence of anv channe in the south-eastern reo'ion : slio-ht freshenino; 
and steejiening of temiierature gradients east and soutli-east of Iceland; sudden 
extension of a salter area westwards just south of lat. 60° N. 
J/ay, 1806.—This month is marked by great rise of teiipjerature, es^iecially in the 
lower latitudes, with the advancinu- season. In the Gulf Sti'eam region the isothermal 
of 20° reaches the 40tli parallel between 55° and 65° W. long., and further east the 
15° line runs Uji to lat. 50°. The 10° and 15° lines have again closed in south-east of 
Nev-Toundland, l)y a change like tliat between January and Feljruary. The 5° line 
lias not moved much, hut the water lietween it and the coast has become warmer, 
the line of 0° noic only f>ff Gajie llace. In mid-Atlantic the rise of 
temjDerature only appears south of 50° N. lat., the 12° and 15° isothermals have 
moved u]), ljut the 10° line remains unclianged. East of long. 30° W. the distribution 
has become more complex, there is everywhere a rise of temiieiuture—the 15° line 
comes uj) to 50" N. lat., and near to the entrance to the English Channel, the 12° line 
touclies the north of Ireland, the 10° line runs u]) to 60° N. north-we.st of Scotland, 
and the 8° line nearly takes the j^lace of the 5° line east of Iceland, although the 
latter has lieen very little disj^laced. But the of the isothermals has altered 
considerably, the axis of maximum temj^erature in the Faeroe-Shetland Channel has 
become more strongly marked—note the two 0° lines, and the “head” of the 10° line— 
the 8° line is bent sharply round at the Faeroe Islands, and to south-east and south of 
Iceland the rise of temiierature from last month is relatively small. West and soutli- 
west of Iceland the isothermals form a small wedge pointing nortliwards, while on 
both sides of the southern extremity of Greenland temperature seems to have fallen 
somewhat. On the west coast of Greenland temperatures are higher north of 
about 62° N. 
Off the coasts of New England and Nova Scotia the fresher waters have retreated 
closer to the land, and the 36 line re-apj^ears. Tliere is little change oft the New¬ 
foundland Banks, but in the lat. 45° to 50° N. long. 40° to 45° W. area the salinity is 
greater. In the south-eastern region the 35‘5 line retains its position, but east of 
long. 20° W. the great l)end of the 36 line has disappeared, and the line runs straight 
on to the middle of the Bay of Biscay. 
North of 50° N. lat. the 35 line has moved iiearA 10° to the west, and it now runs 
nearly straight south along the meiidian of 40° W. In the region between Norway 
and Iceland the lines have become much crowded together ; a patch of water of over 
