Economy in first cost was the guiding consideration in the construction of the cell houses, although a monolithic concrete structure with brick veneered exterior walls is by no means a cheap construction. But it is a permanent and safe construction. Economy in the construction of the cell house was secured through its compactness.
The outside type of cell house can be made practically secure for all classes of prisoners when surrounded by an outside wall of adequate height, with its top guarded by high tension charged wires, provided the windows to the cell houses are barred with steel-proof window guards and the prisoners are reasonably well guarded.
The relative hygienic and physiologic advantages of the outside and inside cell construction I will not discuss here except to say that we considered the outside cell construction manifestly superior in both of these respects. While we consider these features very important in a permanent prison, the question of economy in initial cost was also important in that the outside cell type of prison is a considerably narrower prison for the same cell capacity, and, furthermore, since continuous mechanical ventilation is not essential with the outside cell type, it can be more densely occupied, which further promotes economy in construction.
In designing the outside cell type of prison the problem is one of providing a certain definite external wall area for the sides of the prison, since for given dimensions of cells and a specified number of these cells a definite external wall area is required. The problem of maximum economy in construction then resolves itself into a question of providing the maximum of wall area with the minimum of floor area. Two general forms of outside cell buildings have been proposed: one, the narrow rectangular type adopted at the Kilby prison, and the other the cylindric type. It is demonstrated in geometry that of all figures a circle has a maximum of area for a given length of periphery, while a very narrow rectangle or quadrilateral has a minimum of area for a given periphery. It is, therefore, obvious that for a given external wall area, or a given cell capacity, the narrow rectangular type is more economical in first cost, since it reduces the ceiling and floor area to a minimum.
Economy in construction was also promoted by constructing our cell house five tiers high instead of four tiers, as is more usual.
Finally, additional economy was secured by the use of the multiple man cell. Our multiple man cells accommodate six prisoners, while three single man cells of the same cubic contents containing two partitions, two extra prison doors and locks, two extra lavatories, two extra water-closets, two extra radiators, with all of the necessary connections to these utilities, will only accommodate half as many prisoners. It will, therefore, cost more than twice as much in cell-house construction to incarcerate a given number of prisoners in the single man cells than in the six man cells.
It will, therefore, be noted that we have secured economy in cell-house construction (which is the most expensive item of prison construction) by increasing the density of occupancy in the cell houses. But this density of occupancy carries with it responsibilities in the matter of providing adequate ventilation for the inmates. Recognizing this responsibility, we have designed our cell house to secure the very maximum of natural ventilation. This is secured, first of all, by a very large proportion of window area to wall area; by ventilating the windows top and bottom; by constructing the cell house with a cross-section shaped like a chimney, with a large number of large ventilators on top of an open pitched roof, so as to secure the very maximum of chimney effect and also the very maximum effect from breezes.
Finally, to insure an adequate supply of ventilation in the summer, when there may be neither wind nor temperature difference, we have mounted disc fans in each ventilator, driven by ball-bearing shafting from a push-button-controlled motor. By this means the cell attendants, by pushing a button, will be enabled to flood the cell house with fresh air at any time the air becomes foul, and since the attendants will be on the inside of the prison, where the air will be most foul, they will probably make use of their opportunities.
Apart from humanitarian considerations, which in a large measure should dominate the designer of a prison, there is also the economic question of securing the maximum mental and physical output from the prisoner while at work. In an industrial prison a man can do more and better work if he sleeps and rests sufficiently. If the cotton mills are to be operated double shift during summer months with a large portion of the population sleeping during hot summer days, it is doubly important that the prisoners be confined in well-ventilated and sanitary quarters. This fact we have borne in mind in the design of the cell houses at Kilby Prison.