WILLIAM HAYLEY (1745-1820), the biographer of Cowper, wrote various poetical works, which enjoyed great popularity in their day. His principal productions are the Triumphs of Temper (1781), a series of poetical epistles on history, addressed to Gibbon, and Essays on Painting, on Epic Poetry, &c. He produced several unsuccessful tragedies, a novel, and an Essay on Old Maids. A gentleman by education and fortune, and fond of literary communication, Hayley enjoyed the acquaintance of most of the eminent men of his times. His overstrained sensibility and romantic tastes exposed him to ridicule, yet he was an amiable and benevolent man. It was through his personal application to Pitt that Cowper received his pension. He had (what appears to have been to him a sort of melancholy pride and satisfaction) the task of writing epitaphs for most of his friends, including Mrs. Unwin and Cowper. His life of Cowper appeared in 1803, and three years afterwards it was enlarged by a supplement. Hayley prepared memoirs of his own life, which he disposed of to a publisher on condition of his receiving an annuity for the remainder of his life. This annuity he enjoyed for twelve years. This memoirs appeared in two fine quarto volumes, but they failed to attract attention. Hayley had outlived his popularity, and his smooth but often unmeaning lines had vanished like chaff before the vigorous and natural outpourings of the modern muse. As a specimen of this once much praised poet, we subjoin some lines on the death of his mother, which had the merit of delighting Gibbon, and with which Mr. Southey has remarked Cowper would sympathise deeply.