Bruneseau, in his exploration, proceeded down hill. At the point of separation of the two water-conduits of the Grand-Hurleur, he deciphered upon a projecting stone the date of 1550; this stone indicated the limits where Philibert Delorme, charged by Henri II with visiting the subterranean drains of Paris, had halted. This stone was the mark of the sixteenth century on the sewer; Bruneseau found the handiwork of the seventeenth century once more in the Ponceau drain of the old Rue Vieille-du-Temple, vaulted between 1600 and 1650; and the handiwork of the eighteenth in the western section of the collecting canal, walled and vaulted in 1740. These two vaults, especially the less ancient, that of 1740, were more cracked and decrepit than the masonry of the belt sewer, which dated from 1412, an epoch when the brook of fresh water of Ménilmontant was elevated to the dignity of the Grand Sewer of Paris, an advancement analogous to that of a peasant who should become first valet de chambre to the King; something like Gros-Jean transformed into Lebel.