While at Naples, I received from slaves, redeemed from the province of Constantina, accounts of magnificent ruins they had seen while traversing that country in the camp with their master the Bey. I saw the absolute necessity there was for assistance, without which it was impossible for any one man, however diligent and qualified, to do any thing but bewilder himself. All my endeavours, however, had hitherto been unsuccessful to persuade any Italian to put himself wilfully into the hands of a people constantly looked upon by them in no better light than pirates. While I was providing myself with instruments at London, I thought of one, which, though in a very small form and imperfect state, had been of great entertainment and use to me in former travels; this is called a Camera Obscura, the idea of which I had first taken from the Spectacle de la Nature of the Abbé Vertot. But the present one was constructed upon my own principles; I intrusted the execution of the glasses to Messrs Nairne and Blunt, Mathematical instrument-makers opposite to the Exchange, whom I had usually employed upon such occasions, and with whose capacity and fidelity I had, after frequent trials, the greatest reason to be satisfied. This, when finished, became a large and expensive instrument; but being separated into two pieces, the top and bottom, and folding compactly with hinges, was neither heavy, cumbersome, nor inconvenient, and the charge incurred by the additions and alterations was considerably more than compensated by the advantages which accrued from them. Its body was an hexagon of six-feet diameter, with a conical top; in this, as in a summer-house, the draughtsman sat unseen, and performed his drawing. There is now, I see, one carried as a show about the streets, of nearly the same dimensions, called a Delineator, made on the same principles, and seems to be an exact imitation of mine. By means of this instrument, a person of but a moderate skill in drawing, but habituated to the effect of it, could do more work, and in a better taste, whilst executing views of ruined architecture, in one hour, than the readiest draughtsman, so unassisted, could do in seven; for, with proper care, patience, and attention, not only the elevation, and every part of it, is taken with the utmost truth and justest proportion, but the light and shade, the actual breaches as they stand, vignettes, or little ornamental shrubs, which generally hang from and adorn the projections and edges of the several members, are finely expressed, and beautiful lessons given, how to transport them with effect to any part where they appear to be wanting.