Impedance bridge info ?

Does anyone have any information, such as operating instructions or a
manual (or photocopy of same) for a 'Genral Radio Company' impedance
bridge, type 1650-B ? I recently found this near mint condition
instrument in a junk sale, of all places, but alas, no manual was
included. It looks like just what I've been looking for to mesure C, L,
&R values for my next coil (8"x32" sec. -at- 3 to 5 kva, (maybe more :-)).
Many thanks in advance to anyone who could help!
Tony Greer