[time-nuts] Restoring GR 1120-AB Frequency Standard

Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Aug 20 07:05:36 EDT 2008

phil wrote:
> Bruce, what was the diameter or how was the column situated to give those 
> resolutions.

The thermoregulator consisted of a horizontal ring tube filled with 
toluene connected to a 13" long J -tube filled with mercury and 
containing a capillary section at the top.
The top contact consisted of platinum wire within and parallel to the 
capillary section, the mercury entered the capillary section and made 
contact with the tip of the vertical platinum wire therein.
The other contact was made via a piece of platinum wire sealed through 
the side of the glass tube below the capillary section.
Thus the top contact platinum wire  fine enough to fit within the 
capillary section of the J tube and to a first approximation the 
diameter has no effect on the sensitivity which is due to the relatively 
high thermal expansion of the (highly flammable and somewhat toxic) 

Platinum and iron have the advantage that they do not directly form 
amalgams on contact with mercury and are thus not embrittled by 
However amalgams of platinum and iron can be formed electrochemically.

I have a couple of illustrations of such thermoregulators which I can 
scan if you wish.


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