The solution of the pressing problem was entrusted to Colonel, afterward Sir Joshua, Jebb, a distinguished officer of the Royal Engineers, who was already well known in connection with prison building and with penal legislation generally. He had for some years past been associated with the two official inspectors of prisons; after that he had assisted in the superintendence of Millbank, when constituting a convict depot, and he had been in reality the moving spirit of the commissioners who built the model prison at Pentonville. In those early years he gave undoubted earnest of his energetic character and great powers, a promise more than fulfilled. His proposal was to construct a great breakwater at Portland, largely assisted by the labour of convicts which was abundant and running to waste. He meant in the first instance to provide accommodation of some sort on the island of Portland wherein the convicts might be securely lodged immediately adjoining their works. He described, in a memorandum dated 1847, the style of place he proposed to build. Naturally, he said, when the works on which the prisoners were to be employed were likely to be completed within a limited time, something less costly than a substantial prison would suffice. Safe custody and the due enforcement of discipline must of course be secured; but these might be obtained without any very extravagant outlay. He suggested, therefore, buildings on wooden frames, with corrugated iron partitions; the whole so constructed as to be easily taken to pieces and removed to another site if required. In these buildings the convicts might be kept safe and separate, at the probable cost of little more than £34 per cell. Similar prisons might be run up anywhere, so that the entire number of convicts for whom accommodation was required might be housed for about two hundred thousand pounds. Colonel Jebb accompanied this proposal with certain figures as an off-set against this outlay. He assumed that the maintenance, including every item, would amount to £158,000, but their earnings would be £180,000. The balance was therefore a gain of £22,000--a sufficient interest on the original cost of the prison buildings. These figures were speculative, of course, nor were they found exactly accurate in practice; the cost of maintenance proved undoubtedly higher than thus estimated, but in return the earnings were also considerably more.