MUSEUM OF COMPARATIVE ZOOLOGY, 171 
Having, therefore, tested the value of the improvements, it only re- 
mained for me to put them in a better mechanical shape, and I therefore 
submit the accompanying drawings, which have been withheld for the 
past two years that any slight idea occurring to me might be embraced 
in the general plan. 
Description of the Parts of the Machine. 
The Reel (A, Figs. L, IL, IIL, IV., V.) should be, for convenience, one 
fathom in circumference of drum, and should have a friction score which 
is V-shaped in cross section. ‘When the sinker strikes the bottom, the 
momentum of the reel and its remaining’ wire requires to be quickly 
overcome by the resistance of the friction line, in order that any undue 
slacking and consequent kinking of the wire may be avoided. To secure 
this quick stoppage, the reel should be made as light as the very con- 
siderable strength required for reeling in will permit. In reeling in 
without the reeling-in or strain pulley, it is necessary that the reel 
should be of sufficient strength to resist the accumulated strain of suc- 
cessive convolutions of the wire under strong tension. If a reel can be 
made of light weight and yet capable of bearing this crushing force when 
reeling in from great depths, the strain pulley for reeling in will no longer 
be needed. The reel should be made of iron or steel, as a brass reel 
enwrapped with steel wire would perhaps cause the deterioration of the 
wire through the effects of galvanic action. It is rigidly attached to its 
axle by a key, and the easy removal of the key would be a convenience, 
since the reel without its axle could be stowed into a much smaller 
tank than is necessary when the axle is retained. When a reel contain- 
ing wire is out of use it is generally kept in a tank of oil A crank 
should be provided for each end of the axle. 
The Register (B, Vig. 1.). — The construction of this is sufficiently ex- 
plained by the drawing. It is the same as that used by Sir William 
Thomson, and is worked by a screw-thread attached to the axle of the 
reel. The register evidently does not record fathoms, an interpolation 
being necessary in determining, from the reading of the register, the 
length of wire payed out. It is very handy, however, in keeping an 
approximate account of the wire payed off the reel, so that the correct 
amount of resistance can be applied to the reel. The correction to 
add to the reading of the register is so easily found after the manner 
followed on board the “ Blake,” that the register is desirable also as a 
check on the odometer. 
The Reeling-in or Strain Pulley (0, D, E, Figs. L, IV., V.) is com- 
