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In [9766], Gary recorded a disagreement with my suggestion that one can do
little to protect a sensitive object, such as a crystal oscillator, from
environmental changes in ambient temperature, by such means as wrapping it
in blankets. I claimed that this could have only a short-term effect, and
that the ambient changes would always get through in the end.

He wrote-

"So I disagree with George to the extent that if the watches are kept in
an insulated box, to limit the effect of diurnal changes in cabin
temperatures, then the change in rate will only happen based on long
term changes in ambient temperature, say on a cruise from the Caribbean
to England. But, if the cabin is kept in a range of temperatures which
are habitable for humans then the change of rates can be kept to a small
number."

I recall that as a child, British winters, in a house with only local
heating, were made tolerable at night only by using a hot-water-bottle (such
aids may be unknown and unnecessary in the USA). And I recall how rapidly
such a bottle would lose its heat, though wrapped in blankets with me, so
that before very long it was a pleasure to kick it out. I also recall the
use of a vacuum "Thermos" flask to keep cups of tea hot, and their failure
to do so for more than a very few hours. This in spite of the fact that some
pints of water were involved, a substance which has the highest
specific-heat of any, which means that it holds more heat, and keeps its
temperature, longer than anything else. Gary's crystal oscillator in a
blanket, without such heat-ballast, would not keep the outside temperature
at bay for long, but with a bottle of water to keep it company, he might
increase its thermal time-constant to a few hours; not for days, however.

As for his "range of temperatures which are habitable for humans", there
might well be different views on that from different societies in different
eras. A week ago, I was looking over HMS Cavalier, a World war 2 destroyer
built in 1944; the sort of ship that escorted Arctic convoys to Murmansk and
Archangel in Northern Russia, Summer and Winter. She was refitted in 1957
and retired in 1974. Yet still, she had a completely open bridge, without
windows, and only a dodger to keep the weather off. And I was rather
surprised to find, tucked away on that open bridge, sheltered from rain but
from nothing else, electronic gear such as a radar display.

How, I wonder, would modern American bridge-teams, sheltered from the world
in their air-conditioned cocoons, without even an open bridge-wing to walk
out on to, have fared under such conditions? Or in the environment accepted
by some present-day small-craft sailors, the ones that venture away from
tropical trade-wind sailing?

The "bridge" got its name from an open lattice structure, that bridged the
gap between the top of the paddle-covers, to provide an all-round view. From
such a perch, steamers in their thousands were conducted across the North
Atlantic, the year round.. In thick weather, a lookout was expected to be
stationed at the fo'c'sle head; no shelter provided. These were considered
to be habitable conditions then, but I doubt whether Gary would describe
them so now.

Polar explorers, by the way, would carry sledge chronometers: pocket
watches, slung round their necks inside their furs, essential for guiding
them back to base along the correct longitude. When Shackleton's Endurance
went down in the Antartic ice in 1915, the ship's box-chronometers were
abandoned with the ship, and from then on the expedition relied on four such
pocket-chronometers. Only one of those remained in working order throughout
that remarkable journey from Elephant Island to South Georgia, being
essential for Worsley's feat of small-craft navigation.

Together with Brad, I'm intrigued by the type of yoga that Gary adopts to
enable him to read a chronometer that's duct-taped to his belly.

George.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.


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