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George wrote:

> I've been wondering what's behind the interesting discrepancy that Bill has
> put his finger on, between the position of the Smalls lighthouse on Sumner's
> plate III, and its modern position.

I would have to credit George with unearthing the illustration
discrepancies, or at very least providing the needed puzzle pieces and
pointing out the path.

Following is a summations of the data to date.  All measurements are
approximate.

SMALL'S

Plate III
51d 48' N
5d 38' W

Bowditch
51d 43' N
5d 40' W

George's 1950 gazetteer
51d 43' N
5d 30 W

Small's Rock: Collins (via George)
51d 44' N

TUSKER

Plate III
52d 13'
6d 07' W

Bowditch
52d 12' N
6d 13' W

George's 1950 gazetteer
52d 12' N
6d 12'W

I had been thinking along the same lines as George in that these are indeed
illustrations to demonstrate a method, not actual charts, and also noticed
the truncated longitude scale on the Plate III.  That said, the math should
still work out drawings or not. For clarity, in PhotoShop I layered the
Bowditch illustration over Plate III and scaled the Bowditch illustration to
match the Sumner plate's longitude, as that is one place they do seem to
closely match.  I also created a longitude scale for the Sumner plate.  I
made two versions of this layered illustration.  The first matches up
latitudes between the two, the second the LOP's and Small's within
"tolerable" limits.

If interested in obtaining these two JPEG's, let me know and I'll send them
off list.  If there is enough interest, I'll be happy to upload them.

I feel George has put his finger on it. Some form of poetic license is
afoot.  To have Small's on an intended track of 22.5d from the ship you
either have to move the lighthouse (as per Plate III) or move the ship's DR
(as in Bowditch). Both Sumner and Bowditch seem to fudge or exclude just one
little detail to make it work.  Bowditch omits then fudges the DR, Sumner
appears to move the position of Small's.

The Bowditch illustration seems to moves Small's up to the 1950 (and
Collin's pre-1837) position George posted, but to make the LOP work the DR
was dropped down to approx. 51d 32'.  The online version of Bowditch (Pub 9,
1995) puts Small's at 5d 40' W rather than 5d 30' W, which is close to the
Plate III, but 10' longitude off George's 1950 gazetteer.  Strange indeed.

Tusker, on the other hand, seems to have used that fact that all eyes were
on Small's to laterally migrate at will.  In Plate III it is about 44, not
40 miles from the Sumner's DR.

Past that, Ken's question as to why Sumner may have been a lot closer to
impacting rocks than his DR would predict has been adequately answered.  But
the devil is in the details.

Its been my first history "hunt," so thank all of you for your patience.
Now I appreciate why many of the list are interested in an accurate
centuries-old almanac.

Bill

   

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