Errors in Shi^s Reckonings. 99 
Minute' Glaffes , and fometimes want 
Care, as in fo long a Run caufe often a dif- 
ference of many Leagues in the whole Ac- 
count. 
Mold of my Men that kept Journals im- 
puted it to the Half-Minute-glaffes ; and 
indeed we had not a good Glafs in the Ship 
befide the Half- watch or Two Hour Glaf- 
fes. As for our Half-Minute-Glafles we 
tried them all at feveral times, and we 
found thofe that we had us’d from Brazil 
as much too fhort, as others we had us’d 
before were too long ; which might well 
* make great Errors in thofe feveral Reck- 
onings. A Ship ought therefore to have 
its Glaffes very exaO: ; and befides, an ex- 
traordinary Care ought to be ufed in heav- 
ing the Log, for fear of giving too much 
Stray-Line in a moderate Gale ; and alfo to 
flop quickly in a brisk Gale ; for when a 
Ship runs 8, 9, or lo Knots, half a Knot 
or a Knot is foon run out, and nor heeded : 
But to prevent danger, when a Man thinks 
himfelf near Land, the beft way is to look 
out betimes, and lie by in the Night : for 
a Commander may erreafily himfelf; be- 
fide the Errors of thofe under him, tho’ 
never fo carefully eyed. 
Another thing that {tumbled me here 
was the Variatm?., which, at this time, by 
the laft Amplitude I had I found to be but 
7 deg. 58 min. W. whereas the Variation 
H 2 at 
