42 FRIDTJOF NANSEN. M.-N. Kl. 



tion of a line connecting the ends of these two Hnes will then give the 

 actual movement of the water at the last-mentioned depth [for this method 

 see Nansen, 1906, pp. 29 & 30]. Let us take an example. At station 41, 

 on August 18, between 3.04 and 3.14 a.m. a velocity was observed, at 450 

 metres, of 23.5 cm. per second coming from S 70° E (magnetic); and at 

 100 metres a velocity of 13 cm. per second from S49''E. The depth of 

 the sea was about 490 metres. If we assume that the water had no move- 

 ment at 450 metres, the ship has consequently, during those 10 minutes, 

 been drifting towards S 70° E with a velocity of 23.5 cm. per second, while 

 at the same time the water at 100 metres has been moving towards 

 N 49^ W with a velocity of 13 cm. per second in relation to the ship. If 

 therefore we draw on paper a line 23.5 cm, long, at an angle of S7o°E 

 with the magnetic meridian, and from the end of this line draw another 

 line 13 cm. long towards N 49^ W, the actual current at 100 metres will 

 be represented by a line drawn from the starting-point of the first-line 

 to the termination of the latter line. The current is thus found to be 12.2 

 cm. per second towards NSS^E magnetic or N76^E (true). 



The values obtained in this manner cannot be expected to be very 

 accurate, because on the one hand the directions of the movements 

 are not measured with a sufficiently high accuracy, it being only within 

 ± 10 "^, as the compass-box is divided into chambers of lo*' each. On the 

 other hand it is assumed that the water at 450 metres, near the bottom, 

 has practically no movement. If this assumption is not correct, the velo- 

 cities and directions found for the currents at the higher levels and at the 

 surface will obviously be inaccurate; and the greater the movement of the 

 water near the bottom, the more will this be the case. As will be pointed 

 out later, it is, however, hardly probable that the movements of the water 

 of the deep strata were, as a rule, considerable, and at any rate not at 

 Station 41. 



Another method of measuring the drift of the ship was also attempted. 

 The sounding-lead was sent down into the bottom-mud with as much speed 

 as possible, in order to make it go deep in and stick well. While the 

 sounding-line was then continuously kept as tight as possible without run- 

 ning too great risk of dragging the lead along the bottom, as much line 

 was gradually paid out as was made necessary by the movement of the 

 ship. This was at first done by hand, later by putting a moderate break 

 on to the sounding-winch, so that line was run out when its strain be- 

 came sufficiently great. 



By noting how many metres had to be paid out for every 10 minutes, 

 it should thus be possible to compute the velocity with which the ship was 



