322 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
but it is serviceable for a year, at least, and sometimes lasts two years. This heavy 
wire is recommended for use in depths uot exceeding 500 fathoms. 
The Tanner machines recently made have been simplified in construction by dis- 
l)ensing with the inner and outer shafts and conical friction surfaces for engaging the 
cranks and substituting therefor a single cylindrical shaft with its ends squared for 
the recei)tion of sleeves which form cylindrical bearings for the cranks, both being held 
in place by washers and set screws in the ends of the shaft. The cranks are thrown 
into and out of action by siiriug-controlled locking-bolts, carried on their rear sur- 
faces, which pass through holes in hubs of cranks and into the sleeves. The worm 
wheel and ratchet are carried on the cylindrical body of the shaft, between the sleeves 
and the frame, and arc held with set screws. The reel is also secured in the same 
manner. 
THE TANNEK SOUNDING MACHINE FOK BOAT SERVICE. 
It is frequently desirable to extend lines of soundings from one or two to 
several hundred fathoms, with the same vessel and apparatus, and the Tanner 
machine being well adapted for boat work, was installed at the stern of the Albatross^ 
steam cutter, with fittings sinular to those on board ship, and has performed excellent 
service. 
Cut 45. — The Tauuer souudiiig machine nionuted in the steam cutter. 
When a sounding is about to be taken the cutter is stopped as quickly as prac- 
ticable, manetiveriug to keep the wire vertical during its descent, and as soon as the 
lead strikes bottom she steams ahead again at full speed, the wire being reeled in 
while she is under headway. Short base lines are quickly measured by making the 
stray line fast, setting the register at zero, and steaming directly for the oj)posite end, 
attaching as many floats en route as are necessary to suj)port the wire at the surface. 
The reading of the register is corrected as in sounding. The same method will apply 
on a smooth stretch of land by mooring the boat and walking away with the wire. 
This is not a rigidly accurate method, but, for short lines, the results will be 
found to comi)are favorably with those obtained with the surveyor’s chain. 
