382 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
was SW., and the distance estimated at 4 knots between the first and second sights 
and I to 1 knot from the second to the third. Plotting the track the ship was found 
to have been in positions 1, 3, 3. No current observed. 
OTHER METHODS. 
In addition to the above-mentioned methods, advantage is taken whenever 
possible of the simple “four-point problem” of finding the distance from an object by 
reading the taffrail log when it bears exactly four ijoints off the bow, and again when 
it bears exactly abeam, the distance from the object at the second bearing being equal 
to the distance run between the two, plus or minus the current. 
At each sounding the current is carefully estimated by noting the direction and 
speed of the ship necessary to keep the sounding- wire vertical after the sinker has 
passed below the surface drift. A fair guide is thus afforded as to what allowance 
should be made in shaping the course to the next position, as well as in correcting the 
run uj» to that point. Such help is particularly desirable when clouds by day or night 
l^revent taking frequent observations. 
