It is worthy of remark that in the walls, to the certainly not very great elevation they now generally reach, few doorways are discovered, a circumstance which is by no means easily explained. Small rooms are found without any apparent means of access. Perhaps, in such cases, the doorway was at a certain elevation in the wall, and was approached on both sides by wooden steps, which have long perished, and left no traces of the means of entrance. Of course none of the walls of the houses remain sufficiently high to enable us to judge of the manner in which light was admitted into the rooms, whether from side windows, or from openings in the roof. Probability, however, is in favour of roof-windows being in common use, and an interesting circumstance connected with the excavations at Wroxeter seems decisive as to the material of the windows. Considerable quantities of fine window glass have been found scattered over the floors of the houses, of an average thickness of full one-eighth of an inch, which have been duly deposited in the Museum at Shrewsbury. It is the more curious as it has been the common opinion, until recently, that the Romans, especially in this distant province, did not use window-glass; and the fragments of window-glass which have been found more recently in the excavations on the sites of Roman villas have been much thinner than that found at Wroxeter, and of very inferior quality. It is evident, that some of the rooms, all the walls of which were only walls of separation from other rooms, must have received light from above, or have been quite dark.