(- 4 1 9 ) 
• “ in anfwer to this, the ’Marine-Surveyor is of fuch 
44 a Property, that there is no Neceffity to take Care 
u about its fwimming- and it is a con Rant Truth, 
u peculiar to this Inftrument, that be the Ship’s Moti’-' 
44 on on the Water what it will, whether (he runs one* 
“ Mile fafler or flower than another, yet all fhe runs,: is 
u exadly mark’d on the faid Inflrument, as appears 
44 plainly from fome Tables of Experiments made by 
“ me in the River Thames, for obtaining the gradu- 
64 al jfncreafe and Decreafe of both Ebb and Flood. 
3. “ The firetching and ftrinking of the Log-Line , 
<c is another great Error in the Ufe of the Log j for 
44 when a new Line is firfl us’d, let it be ever fo well 
“ flretched upon Deck, and meafured as true as pof- 
“ fible, it fhrinks after wetting confiderably j and 
“ therefore if we rely on the Line run out for the 
44 Ship’s Diflance, we ought to meafure and alter the 
44 Knots on it every Hour before we ufe it- but I 
44 am well allured that this is feldom done oftner than 
“ once a Week, and fometimes not above once or 
44 twice in a Voyage. What great Depcndance then is 
4: tli ere on a Reckoning kept by the Log .<? Since in- 
44 this Cafe the Line will fhrink fo, as to add Miles to 
44 the o;her Miflakes of every 24 Hours. Again, 
“ when the Line is meafured to its greatefl Degree* 
44 of Shrinking, it is generally left there - and when, 
1 by much Ufe, it comes to flretch again, it is fel- 
44 dom or never mended, although it will flretch be- 
4 - yond what it firfl fhrufik. In Abort, fuch are the 
44 Errors incident to the Log , that I don’t wonder at 
44 our Neighbours the T)atch for preferring their 
44 Chips or an irregular Pulfe to it • which conjee- 
44 tural Reckoning of theirs is obtained after the fol- 
44 lowing Manner. They fix two Marks on the 
44 Side of the Ship at a certain DiRance, when an ex*. 
, J N n n 44 perienced 
