Re: vacuums and tank clocks

Neville Michie

Hi, conventional wisdom had a dewar flask as the best insulated enclosure
as the vacuum did not conduct, and the silvered side had very low emmissivity
to reduce radiation.
But there may be a new technique of using aerogel as an insulant.
Although the material does not have zero emissivity, there are so many
particles that have to emit and absorb in sequence that the transmission
via radiation becomes quite low. (T1**4 - T2**4)**n) as n gets great
and the difference gets small the transmission gets small. Conduction via
air always was small if convection was impossible.
I bought some of this material used for insulating refrigerators on boats,
but as yet have not been able to evaluate it.
Neville Michie

On 30 Aug 2019, at 11:19, Brooke Clarke <> wrote:


The Thermos either had a glass bottle that was easy to break or a steel can which would not hold the high vacuum needed to get good thermal insulation.
Stanley came up with the idea of using a filler which allows trapping the particles that outgas from the steel. Read the two patents for a possible way to do this for a pendulum.

Have Fun,

Brooke Clarke
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.

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