JUNE 20, 1912] 
place first, followed by a rapid fali. On the micro- 
thermometer the effect was clearly shown, but would 
have been missed entirely on an ordinary thermo- 
meter. I have called this peculiar rise and fall of 
temperature the “iceberg effect,’’ and it seems to be 
characteristic, and easily distinguished from the 
small oscillations of temperature found in the open 
sea. It is evident that the iceberg effect is caused 
by the fresh water observed by Pettersson in his tank 
experiments. This fresh water in flowing out from 
the berg starts colder than the sea, and gradually 
becomes warmer as the distance from the berg in- 
creases. At the fringe of this freser water the 
temperature is actually higher than the sea tempera- 
ture owing to the absorption of the sun’s heat. 
(Charts showing these effects are here repro- 
duced from a communication by me to Nature 
of December 1, 1910.) In the open sea the warming 
NATURE 
413 
The limit of the influence appears to be about five 
miles. It has been shown,by Dr. Dawson that the 
shoals in the Bay of Fundy influence the surface 
temperatures, and this is in accord with the present 
results. Taking this into consideration, it appears 
that the micro-thermometer may be of great service 
in telling the presence of land and shoals from a ship 
at sea. 
Recent Experiments with the Micro-thermometer. 
During the trip of the Canadian northern steamer 
Royal George from Halifax to Bristol, I had an 
opportunity of obtaining a record of the sea tempera- 
ture across the Atlantic. The thermometer was 
placed in the circulating water drawn in by the 
pumps. Several interesting facts have been observed. 
The iceberg effect was obtained clearly shown, even 
in the water drawn from a depth of 16 ft. below the 
surface. The sudden change of 
temperature on passing out of the 
Labrador current into the Gulf 
Stream was observed. Here a 
rise of temperature of nearly 10° 
was recorded in about an hour. 
The great steadiness of the tem- 
perature of the Gulf Stream was 
remarkable, since for hundreds of 
miles the variations were not more 
than a quarter of a degree. The 
| 
complete absence of any diurnal 
variation of temperature was very 
marked. One of the most interest- 
ing records was in passing over 
IE 
\Change of Passed abopt /4 Mile 3 
| Ship's Time rors pa at2-21PM.| the great wall separating the 
Cee shallower water about 400 miles 
Passed abut ENie | west of the Irish coast. The 
fram Icebekg at bottom of the ocean rises here 
A oer ee very quickly from about three 
| 
miles to about one-third of a mile. 
Just over this wall the tempera- 
ture rose sharply to a peak about 
14° warmer than the surrounding 
sea, and immediately fell again. 
A possible explanation of this may 
be found in the presence of a 
vertical current of warm water 
along this wall, heated either by 
the greater temperature of the 
earth at these great depths or by 
a submerged crater. No other 
Fic. 2.—Microthermogram of the temperature of the sea. 
of the sea by the sun is oftset by the vertical circula- 
tion, but in the fresher and lighter water this is 
impossible, and the warmer water remains on the 
surface. It may be possible to tell the presence of 
the fresher water by the change in electrical con- 
ductivity, and I have designed a recorder to show 
this, which I hope to have a chance to try at some 
future time. 
Disturbing Influence of Land on the Temperature 
of the Sea. 
One of the most interesting results of the Hudson 
Bay experiments was the effect of land on the 
temperature of the sea. The coast of Labrador 
appears to exert an influence in turning up the colder 
undercurrents of the, Arctic stream. Thus whenever 
the ship steamed in towards the coast-line the 
temperature was found to fall one or two degrees. 
NO. 2225, voL. 89] 
explanation can be given for the 
remarkable and sudden change 
here observed. As the depth of 
the ocean gradually becomes less 
towards the Irish coast, the varia- 
tions of surface temperature 
become more marked. This commenced about 
100 miles off the coast-line. As the coast was 
approached the temperature rose steadily until the 
ship passed at a distance of four miles from the 
Fastnet Lighthouse, when the temperature fell about 
a degree. It rose again as the land was left behind 
through the Irish Sea. 
On approaching Lundy Island the next morning 
the temperature again rose rapidly, to be followed by 
a sharp fall as the ship passed the island at a distance 
of about 300 yards. As soon as the ship steamed up 
the Bristol Channel, within two miles of the Somer- 
setshire coast, the temperature took a rapid fall below 
the open sea temperature, exactly as had been 
observed along the Labrador coast. : 
The rise of temperature on approaching the Irish 
coast and on approaching Lundy Island were very 
similar, and may be characteristic of the influence of 
