NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Refraction
From: Ken Muldrew
Date: 2005 Aug 26, 11:19 -0600
From: Ken Muldrew
Date: 2005 Aug 26, 11:19 -0600
I came across an interesting account of rather extreme refraction recently that shows just how dramatic the effect can be with large temperature gradients. The quote is from: Journal of a Voyage, made by order of the Royal Society, to Churchill River, on the North-West coast of Hudson's Bay; of Thirteen Months Residence in that Country; and of the Voyage back to England; in the years 1768 and 1769; by William Wales. Philosophical Transactions (1683-1775), Vol. 60. (1770), pp. 100-136. "August 7th. About 5 saw the low land of Cape Churchill, bearing from the S. To S.W.b.S. but the haziness of the horizon made the land put on a different appearance every 4' or 5'. I cannot help taking notice of one circumstance, as it appears to me a very remarkable one. Though we saw the land extreamly (sic) plain from off the quarter deck, and, as it were, lifted up in the haze, in the same manner as the ice had always done; yet the man at the mast head declared he could see nothing of it. This appeared so extraordinary to me, that I went to the main-top-mast-head myself to be satisfied of the truth thereof; and though I could see it very plain both before I went up, and after I came down, yet could I see nothing like the appearance of land when I was there. I had often admired the singular appearance of the ice in these parts, which I have seen lifted up 2? or 3? at a distance of 8 or 10 miles, although when we have come to it, we have found it scarcely higher than the surface of the water." Ken Muldrew
