[time-nuts] Dipleidoscope

Larry McDavid lmcdavid at lmceng.com
Tue Nov 10 02:06:55 EST 2015

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?


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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