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I regret not having read Chauvenet's manual, which I expect covers all
this (and hope I can understand the book when I receive it!).  But, how
would this technique allow the transit times to be cancelled.  I
apologize for my lack of comprehension.

Fred Hebard

On Dec 26, 2003, at 7:04 PM, George Huxtable wrote:

> I doubt if there were relays involved in the telegraphs for that
> purpose at
> that time.  Observer A would tap a key when a star crossed (one of
> many)
> hairs in his transit telescope, and then a current pulse would flow
> down
> the wire. At both ends A and B of the wire would be a chronograph,
> which
> was a recording galvanometer, which drew a trace of the resulting
> current-pulses. A single master-clock, somewhere in the system, added
> timing pulses to the trace, at the two ends. Times were recorded at
> both
> ends when a star passed over observer A, and again when the same star
> passed over observer B.
>
> This technique allowed the transit time of the elactrical signals to be
> cancelled out.

   

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