Pipes of lead are occasionally met with in the ruins of the stations, and pipes of burnt clay are of very frequent occurrence. To this circumstance the tradition probably owes its rise. They are not, however, found in the Wall, and when placed in the stations, seem to have served a different purpose. One use to which the tile-tubes have been put has been the transmission of warm air throughout an apartment. The walls of one of the chambers of the ‘baths’ at HUNNUM were lined with them. Others may have been used, especially in high situations, for collecting rain-water from the roofs of the dwellings, and conveying it to cisterns. Besides, the inutility of the contrivance militates against the probability of its adoption: the sentinels at their posts could easily transmit hasty intelligence from end to end, by the voice or by horns, without pipes imbedded in the Wall, which, even if constructed, would probably be useless for such a purpose. This traditionary fiction is probably of more than mediæval antiquity. Xiphiline, in his life of Severus, tells some such marvellous tale about the towers of Byzantium. * * * * * [Sidenote: THE MASONRY OF THE WALL.] A description of the MASONRY of the erections which have passed in review before us will conclude this general examination of the Barrier. The following extract of a letter with which I have been favoured by Robert Rawlinson, esq., Inspector of the Board of Health, will form an excellent introduction to the subject. I have several times thought over the subject of the Roman Wall since I had the pleasure of seeing you. The Romans constructed works with many different kinds of masonry; no doubt all chosen to suit the material used, the place, and the skill of the builders. In Rome, and Italy generally, works of great magnificence were constructed, when the art displayed was equal to the grandeur of the design. Such a work was the famed Arch of Trajan, the Arch of Septimius Severus, the Arch of Constantine, the Baths of Diocletian, and others. In these works, construction of the highest order was used, and the sculptor emulated the architect. The lettered altars and sculptured figures found on the line of ‘the Wall’ must not be compared with the best workmanship of Rome. [Sidenote: NATIVE LABOURERS EMPLOYED.]