by Ritch's journal, that the ice on Great Bear Lake was still perfectly solid, and continued unbroken till the beginning of August; which may be considered the average term of its disruption,[1] being a full month later than Great Slave Lake, between which and Athabasca there is a like difference.
On the evening of the 16th, having observed some signs of an opening in the ice to the east-ward, we removed to an island lying outside the mouth of the river. Here I had a fine observation at midnight of the sun's upper limb, elevated just four minutes above the visible horizon; the height of the eye being eight feet, the temperature 38° imd the barometer assumed at 30 inches. The resulting latitude, using Lynn's admirable tables, is 67° 52′ 59″; the true position was 67° 49′ 54″. On this occasion, therefore, the actual horizontal refraction exceeded the tabular by 3′ 5″; indeed, during the succeeding morning, there was much mirage, indicating a highly refractive state of the atmosphere.[2] The
- ↑ The bay of Fort Franklin, at the head of the grand outlet to the southward, is clear of ice much earlier, but furnishes no criterion of its state on the main body and northern parts of this immense lake.
- ↑ The following year I frequently repeated these midnight observations, between the Coppermine and Cape Barrow, when
