[time-nuts] Dipleidoscope

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Tue Nov 10 00:41:20 EST 2015

On 2015-11-09 15:05, Larry McDavid wrote:
> Actually, it is an Edward John Dent dipleidoscope, or E. J. Dent, not I. E. Dent. But, hand engraving an "I" is much easier than engraving a "J" so many (not all) dipleidoscope covers were in fact engraved, "E. I. Dent."
> This letter substitution is similar to that seen in the often-engraved, "TRVTH" seen on buildings.
> Dent is a famous watch and chronometer maker, with offices in London.
> Edward John Dent designed, but did not live to see built, the famous London Great Clock, popularly known as, "Big Ben."

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)
[The bell and hammers were manufactured separately to Denison's design,
and after only two months operation, the hammers cracked the bell,
blamed on the hammers being more than double the maximum weight
specified by the foundry https://en.wikipedia.org/wiki/Big_Ben#cite_ref-wbfbb_1-3
- a mistake unlikely to have been made by Dent.]
Airy was the Astronomer Royal who established GMT, distributed it via telegraph
wires throughout the UK, and compared time at the top and bottom of deep mine
shafts to calculate gravitational differences and mean earth density: definitely
a Time Nut.

> Surprisingly, the Dent & Company survives today and still produces custom clocks, spanning three centuries of clock making excellence.
> Alas, through personal correspondence, the Dent & Company today seems unaware of the Dent Dipleidoscope.

They misspell it differently twice on their History page under Patents and 1843:
diplied[ao]scope - http://www.dentlondon.com/about/history.php
The company appears to have passed out of the family in the 1960s ending
up with a different family owned jewellery and insignia private company

Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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