When Robertson, after his successful "History of Scotland," was long irresolute in his designs, and still unpractised in that curious research which habitually occupies these men of letters, his admirers had nearly lost his popular productions, had not a fortunate introduction to Dr. BIRCH enabled him to open the clasped books, and to drink of the sealed fountains. ROBERTSON has confessed his inadequate knowledge, and his overflowing gratitude, in letters which I have elsewhere printed. A suggestion by a man of letters has opened the career of many an aspirant. A hint from WALSH conveyed a new conception of English poetry to one of its masters. The celebrated treatise of GROTIUS on "Peace and War" was projected by PEIRESC. It was said of MAGLIABECHI, who knew all books, and never wrote one, that by his diffusive communications he was in some respect concerned in all the great works of his times. Sir ROBERT COTTON greatly assisted CAMDEN and SPEED; and that hermit of literature, BAKER, of Cambridge, was ever supplying with his invaluable researches Burnet, Kennet, Hearne, and Middleton. The concealed aid which men of letters afford authors, may be compared to those subterraneous streams, which, flowing into spacious lakes, are, though unobserved, enlarging the waters which attract the public eye. Count DE CAYLUS, celebrated for his collections, and for his generous patronage of artists, has given the last touches to this picture of the man of letters, with all the delicacy and warmth of a self-painter. "His glory is confined to the mere power which he has of being one day useful to letters and to the arts; for his whole life is employed in collecting materials of which learned men and artists make no use till after the death of him who amassed them. It affords him a very sensible pleasure to labour in hopes of being useful to those who pursue the same course of studies, while there are so great a number who die without discharging the debt which they incur to society." Such a man of letters appears to have been the late Lord WOODHOUSELEE. Mr. Mackenzie, returning from his lordship's literary retirement, meeting Mr. Alison, finely said, that "he hoped he was going to Woodhouselee; for no man could go there without being happier, or return from it without being better."