Today there is a Leeds & Northrup doing business out of the UK specializing in industrial furnace temperature monitoring devices. One of Edward Weston's products was "The Weston Standard Cell" which was a mercury-cadmium battery that provided a very specific DC voltage that didn't change over long periods of time. Cell voltage was nominally 1.018638vdc for most of its life.A Standard Cell provided a reference voltage for calculation of various circuit values or a specific voltage supplied for precision measurement type comparisons.Otto Wolff, from 1900 to 1909, produced the Reichsanstalt-type of resistance standards used at the National Bureau of Standards (NBS.) At the turn of the last century, many precision measurements had to be calculated because the measurement couldn't be made directly since many of the instruments we take for granted today hadn't been developed.
Some of the Resistance Bridges were used to locate shorts in long runs of multi-conductor cable.
L & N was purchased by General Signal Company in the mid-1990s. This L&N box differs from the "shunt-pin" type of R box in that the resistance value desired is just "dialed-in" with the switches. The hard rubber used in L&N equipment has a tendency to turn brown with long-term exposure to light. As can be seen from the property asset decal on the front, this instrument was used a Mount Wilson Observatory.
The long shunt pin with knurled nut allows connection as a potentiometer if desired.
Morris Leeds and Edwin Northrup started Leeds & Northrup in 1903 in Philadelphia, PA to supply precision instruments for scientific experimentation within laboratories, colleges and universities and precision test and calibration instruments for industrial applications.
These would be thermocouples, RTDs and other temperature sensors or transducers.
L&N built precision resistance devices including decade boxes, various types of elaborate potentiometers, fixed resistances along with sensitive galvanometers, individual component-type Wheatstone Bridges and many other types of instruments.
The end result is the desired resistance at the large binding posts.
Also, one could calibrate a device by using the box and moving the shunt pins around for the desired result and then total up the shunted R value and subtract that from the total R (1100 ohms for this box) and that would give the calibration resistance necessary to achieve the result desired. However, it shows the process necessary before "dial in" decade boxes were available.
To select a R value one first has to know the total resistance of the box.