A fuse is a time measuring devise which consists of a burning rope. Normally you ignite it at one end and it burns for pre-assigned time. Given two one-hour fuses, (and nothing else except matches), measure a time interval of 45 min.

It is not known whether the burning speed of a fuse is constant or not. (A fuse may be of non-constant thickness; a half of a fuse length, for example may burn more than 1/2 hour or less than 1/2 hour). So cutting fuses into parts, etc. is not permitted.