Sea Log and Sounding Machine . Ill 
NO. 23. 
Description and Use of a Sea Log , and Sounding Ma- 
chine, invented by Mr. Edward Massey, of Hanley, 
in Staffordshire * 
(With an engraving.) 
TO the nautical reader the advantages resulting from 
a log, that will give a dead reckoning free from error, or 
nearly so, must be sufficiently obvious ; and to others it 
would be superfluous to point them out. The principle, 
on which Mr. Massey^s patent log is constructed, is not 
new; but every application of it to practice has been 
found defective, and this is the difficulty the patentee has 
had to surmount. To understand the manner in which 
it acts, see Plate % where a, fig. 3, is that part of the log 
which registers the distance sailed, and is therefore call- 
ed the register; it contains within itself a set of wheql 
work, which operates upon the fingers of the several in- 
dices, 1, 2, and 3. b is the rotator, a hollow cylinder, 
made air tight, and so nearly of the same specific gravity 
as water, as to float when drawn forwards with the velo- 
city of mere steerage way. On this rotator are fixed four 
vanes placed obliquely. It is then fastened to the regis- 
ter by a cord, c , about six feet !ong:f to the loop hole at 
the other end of the register is secured another line, e, of 
sufficient length to extend beyond the eddy of the vesseFs 
wake. 
The finger on the index 1 revolves once while the log 
moves forward one mile ; that on the index 2 moves once 
round in going ten miles; that on the index 3 makes one 
* Nicholson, vol. 21, p. 245- 
f This cord is shown scarcely one tenth part of its proper length in the 
engraving : it would have been an unnecessary extension of the plate to repre- 
sent it otherwise, as it may so readily be conceived. 
