Hermetically Sealed.
Closed absolutely tight. Glass vessels, such as the bulbs of
incandescent lamps, are hermetically sealed often by melting the glass
together over any opening into their interior.
Heterostatic Method.
A method of using the absolute or attracted disc electrometer. (See
Electrometer Absolute.) The formula for its idiostatic use, q. v.,
involves the determination of d, the distance between the suspended and
fixed discs. As this is difficult to determine the suspended disc and
guard ring may be kept at one potential and the lower fixed disc is then
connected successively with the two points whose potential difference is
to be determined. Their difference is determined by the difference
between d and d', the two distances between the discs. This difference
is the distance through which the micrometer screw is moved. The
heterostatic formula is: