The Irish Quarter days reference article from the English Wikipedia on 24-Jul-2004
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Irish Quarter days

Helping orphans the way you would do it
Quarter days in the Irish calendar were one of the four days that marked the beginning of each quarter of the year. They were traditionally regarded as days for quarterly payment of certain debts, such as farm rents and leasehold payments.

The Irish quarter days fell on four religious festival days that are about three months apart.

The Irish quarter days are no longer generally observed.