Particulars of calls are now passed between trunk centres to a great extent over telegraph circuits superposed upon the trunk lines.
Its inner surface is furnished with ridges beset with series of minute, bristle-like, erect, horny teeth, each of which, when strongly magnified, is seen to be formed of a column of superposed cones, hollowed out at the base and capping each other; the summit or crown of each of these cones is expanded, spatulate, hooked backwards, and often multicuspid.
Settlements belonging to the Stone age, and manufactories of stone implements, burial-grounds of the Bronze epoch, earthen forts and burial-mounds (kurgans) - of this last four different types are known, the earliest belonging to the Bronze period - are superposed, rendering the task of unravelling their several relations one of great difficulty.
These free poles produce a magnetic field which is superposed upon that arising from other sources.
The wire is subject to two superposed magnetizations, the one longitudinal, the other circular, due to the current traversing the wire; the resultant magnetization is consequently in the direction of a screw or spiral round the wire, which will be right-handed or left-handed according as the relation between the two magnetizations is right-handed or left-handed; the magnetic expansion or contraction of the metal along the spiral lines of magnetization produces the Wiedemann twist.