SEA-FISHERIES LABORATORY. 267 
students in this country to have here the following 
brief account of this ingenious instrument.* 
Ekman’s ‘‘ Propell-Strommesser’’ consists essen- 
tially of (1) a propeller with counting mechanism 
attached (A and B, fig. 1); (2) a vane (A, fig. 1), to 
keep the propeller always facing the current; and (3) a 
compass-box (C, fig. 1), by means of which the variations 
of direction in the current are measured. To prevent 
any movement of the propeller while the machine is 
being lowered to the required depth, the propeller is 
fastened by a catch (seen at the top, in A), which is 
released by a messenger. When it is desired to stop the 
apparatus, a second messenger is sent down which brings 
the catch into play again. ‘The revolutions of the 
propeller are read on the dials seen in A, and from these 
the velocity of the current can be calculated. 
The variations in direction are shown as follows: 
By means of an ingenious mechanism, small brass shot 
are allowed to pass through the apparatus at the rate of 
three for every hundred revolutions of the propeller. 
These fall upon the compass needle, shown at C, and run 
down the grooved arm, falling into some of the small 
compartments of the compass-box. As will be seen, the 
K. and W. points are reversed, so that the points shown 
by the box correspond to the direction in which the 
apparatus has been lying. The number of shot found in 
each compartment show for how many revolutions of the 
propeller the instrument has been pointing in that 
direction, and thus one can determine the main 
direction, strength and variations of the current during 
a given time. 
We have tried the Current-meter, both in Port Erin 
*See Ekman, Publications de Circonstance, No. 24, Copenhagen, 
1905. 
