Two volumes which appear to record the temporary borrowing of keys from the Library, noting date, name, number of key, and return of key. Dating from 1953-76 and 1955-76, they appear to have been kept concurrently.
Also one volume, 1955-76, which appears to record more long term loans of keys, noting name, date, and signature (from 1974), and occasionally annotated with date of return of key, lost keys, date of death etc.
[Keys were presumably issued to members of the Society to allow them to enter and use the Philosophical Library at times when it was normally closed to its wider clientele.]