Mr. Saunders, in his “Inquiry, &c.” has come to the conclusion that the _ancient_ Tybourn was the stream which has been _recently_ known by that name. But I think those who will take the trouble to examine this subject thoroughly will come to the conclusion that on this point that inquirer has been deceived. It is evident the facts which came under Mr. Saunders’s notice, in the course of his inquiry, did not entirely square with the supposition which he has adopted. And after all, he is obliged to admit that Westminster extended, and extends, to the stream farther westward than the one he has accepted as its western boundary. This West-bourn, or brook, I take to be the ancient Tybourn—the western boundary of the district described in the charter, dated 951; and the western boundary of St. Margaret’s parish, as defined by the Ecclesiastical Decree of 1222. Lysons, writing at the end of the last century, described the stream which crossed the Tybourn road, now Oxford-street, as a “small bourn, or rivulet _formerly_ called Aye-brook or Eye-brook, and _now_ Tybourn-brook.” In the maps of the sixteenth, seventeenth, and eighteenth centuries we find but _one_ stream delineated as descending from the high ground about Hampstead. In Christopher Saxton’s curious map of 1579; in Speede’s beautiful little map of 1610; in John Seller’s, of 1733; in Morden’s; in Seales’s; in Rocque’s accurate surveys; and in others of less note; we see this stream takes the course of that brook which was at one time called Westbourn, and which I believe was anciently called the Tybourn, and discharges itself into the Thames at Chelsea. The Eye brook on the other hand scarcely appeared before it came to the conduits built by the citizens of London; it then crossed Oxford-street in the valley west of Stratford-place, and emptied itself into a reservoir at the north-eastern corner of “The Deer Park,” or as it is now called “The Green Park.” It appears to have been originally very little larger than the Tychbourn which ran down the Edgeware-road; the former carrying the waters from the southern side of Primrose-hill, the latter from the south of Maida-hill. The Eyebourn, however, was very much increased in size when the superabundant supply from the conduits, which were fed by the water brought from Tybourn, and from springs near the village of Eye, were emptied into it. When the reservoir in the Green Park was enclosed with brick and supplied by the Chelsea Water-works Company from the Thames, this brook was covered in, carried beneath the old reservoir, and converted into a sewer, and is now known by the name of the King’s Scholars Pond Sewer; while the larger stream to the west, the Tybourn or Westbourn, has degenerated into the Ranelagh Sewer.