I found additional information on the meter itself.
Patent Numbers: 2,051,399 & 2,433,165, Simpson Electric Co. Chicago, IL USA Model 127
Any >
I have recently acquired a working, antique Simpson /
> Minneapolis-Honeywell millivoltmeter, model W129A2X1.
> This unit is extremely old and I have had a difficult time tracking
> down any information pertaining to the unit.
>
> On the inside of the case is a condensed chart with reference to
> thermocouple and powerpile readings -- I would presume this unit was
> designed to work with a boiler.
>
> I am hoping someone here may have or know of somewhere/someone that I
> can obtain an operator's manual for this unit -- if there is such a
> thing.
>
> I have recently contacted both Simpson Electric and Honeywell, but have
> yet to hear back from either regarding this interesting device.
>
> As you can see from the attached photos, the casing is somewhat
> delapidated, but is still in a fairly sturdy condition. I took the
> liberty of dismantling the unit in order to replace the four lead wires
> as the originals were basically crumbling apart. I do not know whether
> or not the supplied aligator clips are the originals or not. On the
> bottom of each, they sport the following imprinting:
>
> Mueller Elec. Co.
> Cleveland Ohio U.S.A.
> 60 Series
>
> Any information provided will be greatly appreciated.
>
> Thanks in advance!
>
>