94 
GREENLAND VOYAGE. 
The correspondence of these results is, I conceive, 
decisive as to the accuracy of compass-bearings, 
taken from the Baffin’s main-topgallant-mast- 
lxead. 
The Baffin’s deviation being so very consider¬ 
able, the observations now obtained were of the 
utmost consequence to us. A simple example 
will illustrate this. Suppose the Baffin to sail 
with a fair wind 100 leagues on a SSW. course, 
per compass, [thevariation being 42° W.] and then 
back again 100 leagues on a NNE. course by the 
compass, it is evident, that if there were no de¬ 
viation, or other cause of error, she would return 
exactly to the point from whence she started ; 
but in consequence of the deviation only, her ac¬ 
tual position would prove to be 123 miles to the 
eastward, and 55 to the northward of the place 
from whence she set out; or, sailing 200 leagues 
on a SSW. course per compass, (a course often pur¬ 
sued on the homeward passage from Greenland), 
the error in the reckoning woidd be 86\4 miles too 
far southerly, and 160.8 miles too far westerly! 
That is, the ship would prove to be 189 miles to 
the eastward and northward (or in the direction 
of E. 27° N. true) of her position, as calculated 
without the application of the correction for de¬ 
viation. Such an error existing, without its be¬ 
ing known or compensated, it is evident, might 
be productive of the most fatal consequences. 
