Old frequency meter

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Mddeming-at-aol-dot-com>

Hi All, 
        This weekend, I acquired an old GE panel-mount line frequency meter. 
It is 4" on diameter, the scale is 50 to 70 Hz and will look cool on the new
power supply cabinet. Before I burn it up guessing, does anyone know if this
type goes across the lines like a volt meter, or in-line like an ammeter? 

Matt D.