Lloyd Loar was the famous "acoustic engineer" who helped design the early 1920s Gibson "Master Model" series of instruments, including the fabled F5 mandolin. After he left Gibson in 1924, Mr. Loar started the ViViTone company of Kalamazoo, Michigan, one of the earliest manufacturers devoted to the production of electric instruments. Unfortunately for Lloyd, his ideas were a bit ahead of the curve, and ViViTone went under—but not before making the electric mandolin on the left (I'm pretty sure it's the same instrument in both photos), as well as the electric mandola and mandocello depicted below. Both dated 1933, the 'dola and 'cello are probably the earliest electric examples of either instrument.
On the mandolin, the electronics are mounted in a removable drawer which slides out of the bass side of the rim. The signal is transmitted through the bridge by two long screws into the coil of the pickup beneath. The assembly is labeled "Vivi Tone Mandolin, Patent Applied For, No. 301, Manufactured by Vivi Tone Company, Kalamazoo, Michigan." An ink stamp on the wood reads "Vivi-ToneCompany, 71 West 23th Street, Suite 1520, Masonic Hall, New York City, Gramercy 5-2879."