130 DEPARTMENT OF THE NATAL SERVICE 



8 GEORGE V, A. 1918 



by the fact that Helland-Hansen's observations were made between June 24 and 

 August 10 — at practically tbe same time of year as our own work. 



While the density and salinity records are not being included in this report, for the 

 reasons explained above, it is perhaps worth while remarking in this connection that 

 the observed densities also correspond rather closely with the records obtained in the part 

 of the open Atlantic near Nova Scotia by the Challenger expedition in May 1873. The 

 surface densities for the Challenger stations 49 and 50 are, respectively, 1.02354 and 

 1.02451, the bottom readings for the same stations being 1.02400 and 1.02546. The 

 depth at station 40 was only 85 fathoms, that at station 50 was 1,250 fathoms.^ 



The surface and bottom densities found at our stations I to TV were: — 



Station — 



Surface . 



Bottom 



The surface densities throughout the Bay varied from 10238 (stations VI and 

 VII) to 10248 (station XIII). The bottom densities ran from 10244 (station X) to 

 10252 (stations III and IV). Thus it appears that the density of the waters of the 

 Bay of Fundy corresponds quite closely with that of the neighbouring part of the 

 Atlantic. Once more, no doubt, the thorough mixture brought about by the tides is 

 to be held responsible for this, as it seems improbable. that evaporation in the Bay of 

 Fundy is nearly sufficient to counterbalance the influx of fresh water. 



Helland-Hansen remarks that the high surface temperature shown by his curves 

 "is principally due to the absorption of heat rays from the sun. In places the water 

 is heated by contact with warm air, but this source of heat is of less importance, the 

 temperature of the surface water heing, as a rule, higher than the temperature of the 

 airJ'^ He makes no mention of the time of day at which his readings were made, 

 which, of course, would greatly affect the air temperature — unless he refers to the mean 

 air temperature of the day. All our observations, practically, were made in daylight, 

 and in no case was the air less than 2.2° warmer than the surface water, while in most 

 cases it was considerably more. It may be noted in passing that although three of 

 Helland-Hansen's four stations mentioned above are farther north than the Bay of 

 Fundy, and all four are in the open Atlantic, his lowest surface temperature (that in 

 the Faroe-Shetland channel) is 13°C. — more than 1° higher than the highest reading 

 obtained in the Bay of Fundy. In looking over the records of the Challenger observa- 

 tions^ in July, 18Y3, it is found that at 6 a.m. on the 16th of the month the air tem- 

 perature was as much as 3°F. below that of the surface water in the harbour of Madeira ; 

 but in the majority of eases the air was warmer than the surface water. On the 15th 

 the mean air temperature was 0.1° F. less than the mean surface water temperature, 

 and on the 26th it was 0.5° F. less, but such cases are considerably in the minority. 

 In May, 1873, when the Challenger was in this part of the Atlantic, only in a few cases 

 again did the water temperature exceed the air temperature; and in no case was the 

 mean surface water temperature for the day higher than the mean air temperature, 

 until the 22nd of the month, when the ship had gone south to about the 40th parallel 

 of north latitude. 



The temperature curves for stations I to IV do not show so clearly as did those 

 of 1914 the resemblance between stations II, III, and IV, and the distinct difference 

 from these of station I. The curve for station I shows a peculiar rise in temperature 

 between 40 and 70 fathoms. A similar, though smaller rise occurs at the same depth 



1 Report on the Specific Gravity of Ocean Water, observed on board H.M.S. Challenger 

 during- tVie years 1873-76." By J. Y. Buchanan, pp. 14 and 16. Report on the Scientific Results 

 of the Voj-age of H.M.S. Challenger, Phys. and Chem., Vol. I. 



2 " The Depths of the Ocean," p. 225. (The italics are due to the present writer.) 



3 " Meteorological Observations made during the voyage of H.M.S. Challenger, 1873-76." 

 Report on the Scientific Results of the Voyoge of H.M.S. Challenger, Narrative, Vol. II, 1882. 



