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Bill asked, in a thread labelled "Simple celestial navigation in 1897"-

| Back to Sumner, I eagerly await the results of George's inquiries into
| Small's/Smalls (and other?) "migrating" lighthouse(s).  It was clearly IMHO
| within the abilities of civil engineers to erect such a structure on a
| submerged shoal or foundation circa Smalls # 2.  Is relocation the case, or
| were there measurement problems?

================

Response from George-

I'm still "on the case", investigating that matter. The mystery deepens, rather.

I had expected a definitive answer "within a few days"  from the lighthouse authority for those
waters, Trinity House, as to the position of the predecessor to the present Smalls light, and where
exactly that would have been in Sumner's time (1837). No response so far, but chasing them up
recently, I have found that the lady who promised thus is on annual leave, back on Monday. So Bill
will have to wait 'til then.

The Bodleian library didn't start to acquire charts until the 1880s, but I visited their map room
the other day, and they dug out for me "Cary's improved map of England and Wales", published 1832.
This is a large-format atlas comprising county maps bound together, at 2 miles to the inch. Map 22
is of Pembrokeshire, extending westwards into St George's Channel, with an individual date of 1829.
Although it shows lots of navigational information, including lights, soundings, and tidal streams,
with scales of lat and long, it is basically a land-map, so would not perhaps carry the authority
that a proper sea-chart might hope to claim.

It was reasonably easy to measure off the positions of the Smalls light as given on that map to a
tenth of a mile or so, to be N 51 deg 43.3', W 5deg, 38.8' And as drawn, it appeared to be sitting
on top of the always-above-water Smalls rock. It was shown surrounded by drying rocks and shoal
patches to about half-a-mile away. Outside that area, it's deep water; no chance of planting a
lighthouse there. My guess is that both lighthouses, the old one that Sumner saw in 1837, and the
new one of 1858, were in fact planted on the same rock, for which we have considerable divergence of
position.

Frank had written-

"Here's some historical positional info for  Small's/Smalls Rock lighthouse:
I checked Bowditch 1826, 1842, 1849 and the  position listed in these
editions is
51d 45'N 5d 36'W. That's very likely  the position known to Sumner.

In the 1868 edition the position is about  three miles away:
51d 43'N 5d 40'W.
In the 1883 edition, which is when the  US Navy took over and substantially
re-wrote the book, the position is the same  but more precise:
51d 43' 14"N 5d 40' 9"W.
BTW, in all of these it's  listed as "Small's" (possessive).

In the 1918 edition of Bowditch, the  position for "Smalls Rocks: lighthouse"
(no longer possessive) is listed  as
51d 43' 15"N 5d 40' 15"W.

According to various web sites, the first  Smalls Rocks light was built in
1773 and stood until 1858. It consisted of an  octagonal cabin standing on nine
massive oak posts. A new lighthouse was built  from 1859-1861. It still stands ..."

The best estimate I can make of Sumner's position for Smalls light, as he drew it on his chart in
plate III, is N 51deg 48.4', W 5 deg 37.5', which is several miles North of any of those quoted
positions for the lighthouse. Its real position will have been sufficiently far South of his plotted
"Sumner line" that he would have had little chance of spotting it in the "thick weather" he
describes. So was Sumner guilty of tinkering with the position of Smalls light, to make a better
story? The evidence, so far, seems to point that way. It will become more definite, one way or the
other, if and when Trinity House responds.

========================

I think it was Frank who wrote-

|>"...With all the talk recently on Sumner's method, I  think it's worth
| > remembering that Sumner's lines were considered a somewhat  exotic technique,
| > one that might never be used in months at sea. Celestial lines  of position
| > didn't catch on universally until almost a century after Sumner  published.
| > And why that was the case is still a fascinating  question..."

To me, that's one of those sweeping statements, that cries out for a bit of backup evidence. There
is much evidence to the contrary. In his "Wrinkles in practical navigation" (1881), Lecky, a
practical navigator if ever there was one, and no academic, states that his chapters XI, on Sumner
Lines, and XII, on Double Altitudes, are the most important in the book. He tells us that within a
year of Sumner's publication, an order was given to supply a copy to every ship in the US Navy!

So I wonder whether that statement is based on a biased sample of navigationally backward or
ultra-conservative mariners; such as, perhaps, American whaling vessels. |

George.

contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

   

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