Review of Bering’s First Expedition, 1725-30. 117 
method was not very much worse than the others in its results. 
Although there are several typographic or other errors in his 
table of itinerary which render exact comparisons impossible, it 
may be said that the error of the pedometric method, including 
the passage by sea from Okhotsk to Kamchatka, averages about 
two degrees or sixty geographical miles. In the cases of Okhotsk 
and Bolsheretsk the error is one of excess; in the case of the 
cape at the mouth of the Kamchatka river and of the turning 
point of the expedition north of Bering Strait, the result is too 
small by about the same amount. 
That his chart and his revised list of positions should differ as 
they do, is quite as likely the result of the careless way in which 
the minutiz of such work were generally regarded at that day, as 
to any difference of date, or of intentional modification. 
To conclude our review of the instrumental means and methods 
then in use, it may be said that the compasses in use at that day 
were comparatively roughly made and more or less inaccurate. 
The variation was determined in a given latitude by the azimuth 
of the Polestar or the sun at setting observed by means of sights 
attached to the rim of the compass, which was a method accurate 
enough for the general purposes of navigation. The distance run 
was measured on shipboard by the log which was in about the 
same form and perfection as at present, being a very ancient 
invention. 
The survey of a general coast-line was made by compass bear- 
ings on prominent points, repeated from successive stations, the 
distances of the ship’s course being determined by the log and 
the courses by compass, with corrections for current and the varia- 
tion. The lines thus obtained were checked by latitude observa- 
tions made with Davis’ backstaff when the weather permitted. 
Apart from any of the methods mentioned it seems to have 
been overlooked that Bering might have corrected the longitudes 
of the N.E. Siberian coast by the ordinary dead reckoning kept 
on board his vessel, provided he started by adopting the longitude 
for the southern part of Kamchatka peninsula which was in com- 
mon use on many of the charts of his day. Though it is true 
that the maps of that part of Siberia north and northeast from 
the Okhotsk sea were many degrees in error in the longitude, this 
observation does not hold good in regard to the southern end of 
Kamchatka. The work of the Jesuit fathers in China had 
already determined fairly well the position of China and Korea, 
