These expedients, however, could not materially enlarge the space available for graves, and the _fossors_ were driven to excavate another flat (so to speak) either above or below the first. And here they were enabled more easily to provide chambers in which the faithful could assemble in time of persecution. The first subterranean chambers had been made small and plain, and rectangular in shape—mere family vaults apparently; but in the second and third floors we find them both more numerous, more spacious, and in a greater variety of forms, furnished also with _luminaria_, or shafts communicating with the surface of the ground, whereby light and air could be supplied to those who were assembled below. Some of them were decorated with cornices, columns, pilasters, brackets and chairs, hewn out of the solid rock. To the period of persecution belong also those galleries which connect parts of the more important cemeteries with the sandpits in their immediate neighbourhood—connections which were both studiously concealed, and, in some instances at least, designedly rendered dangerous to the use of strangers. [Illustration: _Diogenes the Fossor._] Other features in the development of the architecture of the Catacombs must be passed over, as they cannot be appreciated except by means of a personal examination on the spot, or with the aid of more abundant plans and drawings than our present limits will allow. We must not, however, omit to say a few words about the noble band of workmen by whom these stupendous excavations were being made. We learn something about them even from the Catacombs themselves. Here and there, among the decorations of some of the vaults, may be seen the figures of men armed with pickaxes and lamps, and other instruments necessary for subterranean excavation, and several epitaphs have preserved to us the official title of these men: they were called _fossores_, or diggers. Their work must have been extremely laborious, and hence, in the imperial laws of the fourth and fifth centuries, they appear under a name derived from this circumstance. They are there called _copiatæ_, or labourers _par excellence_; but in all the inscriptions hitherto discovered in the Catacombs, they never have any other name than _fossores_, or _fossarii_. Their life must also have been one of continual danger and self-sacrifice. It was no mere venal service which they rendered to the Church, but a work of real devotedness. Moreover, they were necessarily in the confidence of the Church’s rulers; they knew the exact place of burial of each martyr and confessor, the times and places appointed for the celebration of the holy mysteries, and so forth. We are not surprised, therefore, to hear, on the authority of St. Jerome, that they were reckoned among the _clerics_; and although they are not mentioned in the list of the Roman clergy sent to St. Cyprian about A.D. 240, we find them enumerated in an