The details of the indicator work vary in different libraries. In some it is only used to indicate whether the books are out or in, and one of the many systems of card charging or book-keeping in vogue is worked with it. In the Lambeth libraries no entry is made in the metal slide at the time of issue, but it and the borrower's ticket are placed in one of the divisions of a tray made for the purpose, and the entry is made at leisure by a senior assistant. This is found to be a great help on busy nights, the whole attention of the staff being given to the actual issue, and the entering up can be left until the next morning.
The "Duplex" Indicator, in use at the Aberdeen library, consists of a frame with shelves, as in the " Elliot," but large enough to take a block of wood 4 inches by 2½ inches, and ⅜ of an inch in thickness. The block has pasted on one side a piece of ruled paper to receive a record of the issues. On one end is pasted the author and title of the book, as well as the shelf number; on the opposite end the shelf number only. The borrower upon joining the library is given a reader's ticket, and chooses a book from the indicator, those only being in of which the author's name, title, and number are visible. The attendant takes the block out of the indicator, obtains the book from the shelf, dates it, and gives it to the borrower. He then enters upon the wood block the number of the reader's ticket, and places block and ticket in a tray, which completes the process for the time being. The next morning (supposing that 500 books have
