EJS, you can easily determine whether or not the screw that holds the wall plate over the outlet is grounded, by using a multimeter or a cheap neon bulb AC tester to see if 120 volts or so exists between that screw and one of the two slots in the receptacle (the smaller one if they are unequal in size).
Obviously, if you do that don't touch the metal tips at the end of the test leads while they are in contact with the outlet.
According to this Wikipedia article, knob and tube wiring was in common use in North America "from about 1880 to the 1930s."
Regards,
-- Al
Obviously, if you do that don't touch the metal tips at the end of the test leads while they are in contact with the outlet.
According to this Wikipedia article, knob and tube wiring was in common use in North America "from about 1880 to the 1930s."
Regards,
-- Al