A boon to those with poor circulation and cold feet. If the feet are kept warm the body will be less subject to the complaints arising from colds. These Electric Insoles contain the pure polished metals arranged in such a manner that a mild pleasant current is produced along the soles of the feet, which stimulates the blood and keeps it circulating constantly. They are worn with good results for cold feet, and to keep the feet dry.
-- "Sears Roebuck and Co." 1902 catalogue