With the goal of preventing confusion, let me clarify that the Dent
dipleidoscope is not a mechanical clock at all but rather a purely
optical instrument that makes identification of the instant of local
solar noon easy.
It was used to set mechanical clocks accurately in the period when
trains in England began to be scheduled (and, actually run) on minute
time tables; suddenly, accurate time became important to the common man!
Sundials were used to set clocks previously but common garden horizontal
sundials were accurate to not even 5 minutes; the dipleidoscope could
identify local noon within 6 seconds easily.
In fact, Dent did not invent the dipleidoscope; James Bloxam did but
used prisms, very difficult and expensive to manufacture in 1850. Bloxam
sold the patent to Dent and Dent converted the optics to mirrors and
used his mechanical clock manufacturing business to produce the
dipleidoscope that was then widely sold. It is an astonishingly easy to
use device!
Today, TimeNuts chase lots more time digits of resolution; things have
changed! But, if you don't have any form of electronics, what can you do?
Larry
On 11/9/2015 9:41 PM, Brian Inglis wrote:
...
Dent manufactured to Denison's design (later ennobled as Grimthorpe and
that name
used for the three-legged gravity escapement in that clock and others - see
http://trin-hosts.trin.cam.ac.uk/clock for measurements of a similar clock)
and Airy's specs (including first stroke of the hour to be within one
second
of GMT and performance telegraphed to Greenwich for checking)
http://www.parliament.uk/about/living-heritage/building/palace/big-ben/building-clock-tower/building-great-clock
...
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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