Another point to which the Society devoted infinite pains was the preparation of plans for the guidance of architects in the construction of prisons. A very valuable volume published by the Society traced the progress of prison architecture from the days when the gaol was the mere annexe of the baronial or episcopal castle, or a dungeon above or below the gate of a town, to the first attempts at systematic reconstruction carried out under the advice and supervision of Howard.[72] It is interesting to observe that the plan of "radiation," by which the prison blocks radiated from a central hall, like spokes in a wheel, was introduced as early as 1790 by Mr. Blackburn, an architect of eminence who was very largely employed in the erection of prison buildings at the close of the last century. With some important modifications this principle of radiation is still the rule. The Society did not limit its remarks to the description of what had already been done, but it offered suggestions for future buildings, with numerous carefully-executed drawings and designs of the model it recommended for imitation. Experience has since shown that in some respects these plans are defective, especially in the placing of the governor's residence in the centre of the prison. It was thought that this would guarantee constant supervision and inspection, but it did nothing of the kind, and only the presence of warders on duty is found now-a-days to be really efficacious. The main recommendations, however, are based upon common sense, and none are more commendable than that which deprecates the excessive ornamentation of the external parts of the edifice. "The new gaols," as Howard says, "having pompous fronts, appear like palaces to the lower class of people, and many persons are against them on this account." The Prison Society reproves the misdirected efforts of ambitious architects, who by a lavish and improvident expenditure of public money sought to "rank the prisons they built among the most splendid buildings of the city or town." Absence of embellishment is in perfect unison with the character of the establishment. These are principles fully recognized now-a-days, and it may fairly be conceded that the Prison Discipline Society's ideal differed little from that kept in view in the construction of the latest and best modern gaols.