Gaylord find calculator
This fine calculator sold by Gaylord was used to calculate library fines. The library staff would use such device to determine the number of days that the borrower had to be responsible for the charges. Since the fine did not include the days when the library was closed, it got complicated to do the computation. The Gaylord fine calculator helped the staff expedite the computation of the proper charge made for a return book.
There is a patent filed for such computing device in 1951. The patent number is 2,553,915.
Today, the ebooks have made such computing device obsolete, because ebooks do not accrue fines, as they cannot be overdue.