single terminal tranny's

Hi all,
	I have found two  h.v.transformers with only one output terminal. One of
them is an obit with 20 ma -at-15 kv output, the other is bigger without the
nameplate so I don't know it's spec yet . I will run it up on the variac
and try to establish it's voltage. What would be the best way to utilize
these transformers in a coil?

many thanks

bob golding