( 4 * 5 ) 
1 come now to the Explanation of three feveral 
Dials, any one of which may be ufed with this Ma- 
chine. 
The firfi Dial had three Indexes, one of which 
mark’d io Revolutions of the Engine, each Revolu- 
tion io feet j fo that of conlequence the whole 
Round of the Circle was ioo Feet. As *five of thefe 
Revolutions make 50 Feet, which I reckon to be (or 
at leaffc fhould be) the Difiance marked between each 
Knot on the Log-Line now in Ufe at Sea j by holding 
the Half-minute Glafs in one’s Hand (which is always 
tiled with the Log-Line) one may, by Jnfpedion, fee 
how many Times 50 Feet (he runs in half a Minute, 
and of courfe how many Miles in an Hour, without 
the Trouble of employing four or five Hands, as 
there generally is, in heaving the Log. My fecond 
Index on this Dial marked 100 Revolutions which 
makes 1 000 Feet, as the third Index did 1000 Revo- 
lutions, which is equal to 10, coo Feet j and then a 
little Bell (truck, fignifying when the Ship had failed 
that Di fiance, which may be alfo fitted to firike to 
any other Meafure. 
My fecond Dial had the Circle on its Plate divided 
into twelve Parts, fo that as the Index paft each DK 
vilion, the Ship had run one Mile, and confequently 
twelve Miles, when it had meafured the Circumfe- 
rence. On one Side of this Dial, I had fixed another 
Plate, which was graduated in fuch Manner, that by 
the Half-minute Glafs 1 could alfo, by Infpeftion 
tell what the Veflel run in that Space of Time <&c * 
On my third Dial I had three Circles j the firfi was^ 
io divided, as to fhew when the Ship had run 60 
Leagues ; the fecond was fo contrived, as to fiiew 
when the Ship had run the fame Difiance in Miles- 
and on the third was mark’d 120 Knots • fo that, com- 
puting. 
