Cell Tester

• alternative name: Jewell

0 to 1V = Discharge
1V to 1.5V graduated part of scale
2V full scale

It could have been for testing  Edison "Nickel Iron" cells in Car and other batteries  (Made 1903 to 1972) as they are about 1.67V on trickle charge. The open cicuit voltage is 1.4 volts, dropping to 1.2 volts during discharge.

Or possibly to test large "Igniter"/No. 6/"Flag" type Zinc Carbon 1.5V Cells (screw terminal tops) by pressing the top clips on the terminals. The "wavy" part is likely a high current drain load for cell under test. A 1.5V Zinc Carbon battery is discharged at 0.9V to 1V and is a nominal 1.4V on load, with a no load new cell as high as 1.7V

A 2V Lead Acid Cell is discharged at about 1.6V and is close to 2.3V when fully charged so seems less likely.

In questo link sono elencati 186 modelli, di cui 161 con immagini e 98 con schemi.
Elenco delle radio e altri apparecchi della Weston Electrical Instrument Co.; Newark, N.J.; (Jewell Electrical Instrument Co.; Chicago, IL)