his successors in the Kellogg Company, is shown in Fig. 43. In this,
the electrode chamber, instead of being mounted in a stationary and
rigid position, as in the case of the White instrument, is mounted on,
and, in fact, forms a part of the diaphragm. The electrode which is
associated with the mica washer instead of moving with the diaphragm,
as in the White instrument, is rigidly connected to a bridge so as to
be as free as possible from all vibrations.

Referring to Fig. 43, which is a horizontal cross-section of the
instrument, _1_ indicates the diaphragm. This is of aluminum and it
has in its center a forwardly deflected portion forming a chamber for
the electrodes. The front electrode _2_ of carbon is backed by a disk
of brass and rigidly secured in the front of this chamber, as clearly
indicated. The rear electrode _3_, also of carbon, is backed by a disk
of brass, and is clamped against the central portion of a mica disk by
means of the enlarged head of stud _6_. A nut _7_, engaging the end of
a screw-threaded shank from the back of the rear electrode, serves to
bind these two parts together securely, clamping the mica washer
between them. The outer edge of the mica washer is clamped to the
main diaphragm _1_ by an aluminum ring and rivets, as clearly
indicated. It is seen, therefore, that the diaphragm itself contains
the electrode chamber as an integral part thereof. The entire
structure of the diaphragm, the front and back electrodes, and the
granular carbon within are permanently assembled in the factory and
cannot be dissociated without destroying some of the parts. The rear
electrode is held rigidly in place by the bridge _5_ and the stud _6_,
this stud passing through a block _9_ mounted on the bridge but
insulated from it. The stud _6_ is clamped in the block _9_ by means
of the set screw _8_, so as to hold the rear electrode in proper
position after this position has been determined.