1906. No.3. AMUNDSEN’S OCEANOGRAPHIC OBSERVATIONS IN 1901. 95 
Vil. The Bottom-Water of the North Polar Basin. 
In the North Polar Basin the bottom-water has a minimum temperature 
of between —0'8* C. and —o9° C. according to the observations made 
during the drift of the “Fram” 1. The salinity should, according to the deter- 
1 Professor Otto Pettesson (Geograph. Journal, London, vol. XXIV, 1904, pp. 317— 318) 
appears to be somewhat doubtful as to the accuracy of the temperature determinations taken 
on the "Fram”, and he even says that it is just as "possible that the temperature and 
salinity (of the bottom-water of the North Polar Basin) are lower than in the adjacent 
part of the Norwegian Sea as that they are higher”. It is not quite clear how Petters- 
son can have got this idea. It was pointed out, in the Memoir on the Oceanography 
of the North Polar Basin, that the determinations of specific gravity (and salinity) are 
not as accurate as would have been desirable; this is to be ascribed to the inherent defects, 
of the methods then generally in use. But, as will be mentioned latter, there is no 
possibility whatever that the salinity of the bottom-water of the North Polar Basin, is 
lower than that of the Norwegian Sea. The inaccuracies of the determinations of spe- 
cific gravity, when treated in the way employed helow, are not greater than, for in- 
stance, the inaccuracies of the salinities which Pettersson has published in the series 
of observations from Arrhenius’s Stations in 1896, and the Stations of Kolthoffs expe- 
dition with the Frithjof, in 1900; the values obtained, inasmuch as none of them are 
accurate, are so far fairly comparable. The only observations of salinities, hitherto 
published from the northern part of the Norwegian Sea, to give a considerably higher 
order of accuracy, are those of Amundsen in 1901; and the observations of Dr. 
Hjort, on the "Michael Sars”, east of Bear Island and Spitsbergen in 1900 and 1901. 
As to the temperatures observed in the North Polar Basin even they are not as 
accurate as they ought to be, but they are at any rate much more accurate than, for 
instance, those published from Arrhenius’s Stations in 1896 and Kolthoff’s Stations in 
1900 (where there are evident errors exceeding 0'5° C., or at some of Arrhenius's Sta- 
tions even more than 1° C.). The errors in the final (op. cif., pp. 244—256) temperature 
values of the Qpttom-water in the North Polar Basin cannot, at any rate for the series 
from the summer-months, be more than + 0'1" C. but are probably in most cases much 
less, as is proved by the conformity between the observations at different depths and 
at different Stations. Pettersson does not apparently approve of the use of “probable correc- 
tions”. It would certainly be a great advantage if the zero-corrections of the instru- 
ments used could be accurately determined before and after each series of observations, 
but this could not be done during the Fram-expedition, as there was no pure snow or 
ice available for it; and then there is no other course to follow than to use "probable” 
corrections, if any probable results at all are to be obtained. Prof. Pettersson mentions 
(loc. cit. p. 317) as an example to prove the probable inaccuracy of our temperature- 
determinations Dr. Blessing's observation from 1900 metres at Stat. 24, on Dec. 2, 1995, 
where the reading was —0'65° C. (Oceanography of N. P. Basin, p. 131). Pettersson 
thinks that according to the very careful and complete information given in the Memoir 
about the thermometer used (Negretti and Zambra Reversing Thermometer No. 75,680) 
it must be regarded as uncertain whether this reading should after correction, indicate 
a temperature of —1'05? C., or —0'77° C., or —o’71° C., or —0'65? C. As it is impor- 
tant to know whether Pettersson's doubt is justified, and just how far these observations 
are trustworthy, it is worth while making the following remarks here, whilst at the 
