Purchase a reproduction of this item on VintageMaineImages.com.
This model had been in development for some time before its introduction in 1911, but Sangamo had to wait for the Tesla patents, owned by Westinghouse, to expire.
This induction-type meter uses fluctuations in magnetic fields to turn the rotating disk, while a drag, or lag, magnet keeps the disk turning at a rate proportional to the current.
Please post your comment below to share with others. If you'd like to privately share a comment or correction with MMN staff, please use this form.