[GreenKeys] What is this?

[COURYHOUSE at aol.com]

what is  funny is  leeds and lorthrop  made the wood   box  pretty stuff 
later than   you might imagine...  i will  have to  get  some catalogs out  
and  
 
 
In a message dated 8/23/2013 11:16:25 A.M. US Mountain Standard Time,  
k1lky68 at gmail.com writes:


On  Aug 22, 2013, at 9:27 PM, Lester Veenstra <Lester at veenstras.com>  wrote:

> Resistance standard

As Couryhouse  mentioned:

That thing is a selectable resistance device of ancient  times meant for 
use as a wheatstone (or other) bridge.  The  Guitar-Tuning-Peg-Like things 
make the connections in tight fitting holes -  provide very low resistance 
contacts (If clean).  

Appears to have  binding posts for galvanometer (to detect a null) a 
battery, and the  unknown.  The resistances seem to be arranged to  provide a  
multiplier leg and two or three other legs of a bridge circuit.

My  guess is that it dates from the early 1900's.  I would expect the thing 
 to have held its accuracy well. (I have two perhaps contemporary rotary 
switch  decade boxes made in Germany - they have surprisingly accurate steps - 
all  made of lacquered brass and ebony-like knobs in furniture wood  cases.)

Some similar devices had provision for a water or oil bath to  surround the 
resistance elements for temperature control leading to increased  accuracy.

A true artifact of days long gone by.

Roy

Roy  Morgan
k1lky at earthlink.net
K1LKY Since 1958 - Keep 'em  Glowing!



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