THE ANSCHtYTZ GYRO-COMPASS   227

by increases the thermal conductivity of the porous material; (d) the high thermal conductivity of hydrogen improves the rate of transfer of heat across the film of contact; (e) since hydrogen displaces the oxygen that otherwise would be in the pores of the insulating material, damage of the insulation due to corona discharge is prevented.

136. The Supporting System. - The spherical shell B containing the sensitive element A is hung by six arms, DD, Figs. 178 and 179, to a vertical spindle 8 supported by ball bearings on the top of a bowl E which in turn is carried by the gimbal rings of the

binnacle F. Attached to the vertical spindle are a horizontal gear H connected by a pinion to a reversing motor M, the compass card C, and five collector rings J which serve to connect electrically the master compass to the outside part of the equipment.

Wires from the collector rings extend down the supporting arms DD to the outer spherical shell B. One collector ring is connected to the two equatorial electrodes KK', another is connected to the polar electrode PI, and another to the polar electrode P2. The other two collector rings are connected to two electrodes LI, L2 attached to the spherical shell midway between the two equatorial electrodes K K'. The electrodes LI and L2 are called the " followup " electrodes.

A top view of the compass removed from the binnacle is shown