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THE THOMSON-HOUSTON ELECTRIC LIGHTING SYSTEM.


The generator is known as the "Thomson spherical," on account of the
nearly spherical form of its armature, and differs radically from all
others in all essential portions, viz., its field magnets, armature,
and winding thereof, and in its commutator; both in principle and
construction, and, besides, it is provided with an automatic
regulator, an attachment not applied to other generators. The annexed
view of the complete machine will convey an idea of the general
appearance and disposition of its parts.

The revolving armature which generates the electrical current is made
internally of a hollow shell of soft iron secured to the central
portion of the shaft between the bearings, and is wound externally
with a copper conducting wire, constituting three coils or helices
surrounding the armature, which coils are, however, permanently
joined, and in reality act as a single three-branched wire.

This wire, being wound on the exterior of the armature, is fully
exposed to the powerful magnetic influence of the field poles, which
inclose the armature almost completely. The armature will thus be seen
to be thoroughly incased and protected, at the same time that all the
wire upon it is subject to a powerful action of the surrounding
magnets, resulting in an economy in the generation of current in its