Widener Library will institute on April 7 a special fine of 31 a day for overdue books which have been recalled.

"It's one of a number of things we are doing to improve our recall system." Foster M. Palmer, associate librarian for reference and circulation in the Harvard College Library, said yesterday. The new fine will begin a week after a recall notice has been mailed.

The new fine is aimed at chronic violators who ignore recall polices and pay only 10 cents a day for each overdue book. It will apply to students and teaching follows. Professors, including assistance professors, are exempt from the fine.

The old fine of 10 cents a day on overdue books that have not been recalled will be kept.