What is hog oilers?

Hog oilers were devices used in the early 1900s to keep swine healthy and clean. They were essentially oil dispensers fitted with a rotating brush, that allowed hogs to rub themselves against it to remove dirt and parasites. They were invented by a farmer in Nebraska named JL Robinson in 1907, and quickly gained popularity throughout the United States. Hog oilers were typically made of metal or wood and ranged in size from small, hand held versions to large, stationary ones measuring several feet in length. They were filled with various oils, including mineral oil and kerosene, which were believed to help control lice and other pests that plagued swine. Although they fell out of use in the mid-20th century due to advances in pig farming, hog oilers are still used by some small scale farmers and collectors today as a nostalgic reminder of a bygone era.