1826 J. Wilson Noctes Ambrosianae xxvi, in June 755 The murmurs o' the sheep-washing Yarrow.
1866 2nd Ser. 2 371 A sheep-washing day on the Wye.
1899 T. C. Allbutt et al. VIII. 929 Workmen exposed to the use of arsenical pigments..as in sheep-washing.