s of open and closcd by a hard rubber knob at the outer end, and hard rubber ring | circuit. or base-piece near the end inserted in the wall. The two table-top near the poles of the magnet, but not touching The electrical impulses may be controlled by hand or by halves of the hook are connected… … according to the kind of call required, attached to the revolv- dragon-fly, with mica wings attached to the vibratory spring ELECTRICAL BUTTERFLY. ing spindle of a spring motor and touched by a contact and striped with asphaltum varnish, in imitation of nature. spring, makes a good interrupter for…
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