Arrowsmith's maps were regularly updated with the latest discoveries.
The above map from 1850 now has Boothia correctly attached to the mainland, thanks to John Rae's 1847 survey of the western shore of Boothia Gulf, and it includes Peel Sound, discovered by James Ross in the spring of 1849. Bellot Strait had not yet been found so North Somerset is shown contiguous with Boothia. The West coast of Boothia, denoted by a dotted line, is a guess which would later prove to be remarkably accurate.
Both the main map and the lower strip now uses Dease and Simpson's longitude values for the coastline South of King William Island.
In the lower strip, King William Island is still connected to Boothia by a spindly isthmus - a guess which would later prove to be remarkably inaccurate. The imaginary Poctes Bay has now morphed into Poets Bay, which John Ross had surely intended, to balance Artists bay opposite.
In the main map the geography to the West of KWI is somewhat ambiguous with the supposed isthmus lacking a southern coastline so that the blue wash representing the sea is divided only by a single dashed line. This could be considered the first depiction of the track which would be sailed by Roald Amundsen in his epic transit of the Passage more than fifty years later.
Cornwallis and Bathurst Islands are shown joined, a detail which wouldn't be corrected until the Victory Point record revealed that Erebus and Terror had passed between them en-route to Beechey Island.
Rae's 1854 survey of the West coast of Boothia has proven that King William Island is just that and Bellot Strait also confers island status on North Somerset.
The colouring, Red for the Hudson's Bay Company's discoveries and Blue for the Royal Navy's, is slightly inaccurate as the coast South of Cape Colville (charted by Rae) is wrongly coloured blue and the unsurveyed West side of King William Island should not be coloured at all.
Ironically if this had been the best map which Amundsen had had before he set off he may well have shared the fate of Franklin.
Arrowsmith's 1855 map gives no hint as to the existence of McClintock Channel. That strait between Prince of Wales Island and Victoria Island enables masses of heavy ice to drift South into Victoria Strait where it is trapped against the barrier formed by Royal Geographical Society Islands and the Crozier Peninsula on the West side of King William Island.
Without this information, and the knowledge, which McClintock learned from the inuit, that the was open water in Rae Strait during the short Arctic summer, Amundsen may reasonably have chosen the obvious path to the West of King William Island resulting in the Gjoa becoming beset in the same place Erebus and Terror.
Friday, 28 August 2015
Friday, 14 August 2015
|Click through to larger versions|
The well stocked libraries of Erebus and Terror in 1845 will certainly have included at least one copy of this fine engraving by John Arrowsmith - contained within Thomas Simpson's 1843 book: Narrative of the discoveries on the north coast of America: effected by the officers of the Hudson's Bay Company during the years 1836-39.
In compiling this map Arrowsmith was faced with the problem of reconciling some severe contradictions between longitude data from Dease and Simpson's 1839 expedition with the corresponding figures from George Back's 1835 decent of the Great Fish River. For Montreal Island the difference was nearly a whole degree.
Arrowsmith cleverly solved this conundrum by using Dease and Simpson's geography combined with Back's latitude numbers for the main map (in which Montreal Island is shown to the East of Matty Island) while displaying Dease and Simpson's survey unadulterated in the lower panel (which has Montreal to the West of Matty). Later surveys by John Rae would confirm the veracity of Dease and Simpson's measurements.
Other features which later proved to be erroneous are the presumed open water between the mouth of Back's River and the Gulf of Boothia and the isthmus, indicated by dotted lines, connecting King William Island and Boothia Felix.
Franklin would, of course, have been driven to fill in as many of the blank spaces as possible, and to ink in or delete the dotted lines as appropriate. With the good state of preservation to be expected from the cold dark waters of Wilmot & Crampton Bay, it is not beyond the realms of possibility that such a corrected map may one day be revealed.