Old surplus equipment... I don't think it's 'testing equipment' so to speak... like a meter.
Looks as though it's a combination of adjustable components... You can choose a resistance value, capacitance value, etc for use in troubleshooting or development...
Check the calibration date on it. You may be surprised. (it may be a little hard to read). Last calibrated 2011, was due for recalibration in 2013. It was still in service quite recently.
Well I never!!!!!!
Never heard of a Wheatstone bridge......Ohhh, of course..'You' would cross a Wheatstone bridge regularly with sheep jumping off!! Does it happen on your way to work or on your way home?
Actually, this text was with the above picture.
"A Wheatstone bridge is an electrical circuit invented by Samuel Hunter Christie in 1833 and improved and popularized by Sir Charles Wheatstone in 1843."
So, I should have read it to the full stop lol. Will I ever learn!!