Within the prison walls classification of individual prisoners according to crimes, temperament and habits has been of great assistance in their management. In the United States there are two main systems in vogue, that known as the Pennsylvania System and that as the New York System. The former may be defined as the solitary cellular system, and the latter as the single cell system, with prisoners working and dining together. The Pennsylvania system had its origin in the celebrated Cherry Hill prison, built in 1821 to 1829, containing over 600 separate cells for continuous solitary confinement. This solitary confinement in large airy rooms is expensive but is considered as the best treatment of prisoners. Here the prisoner is kept at work, or instructed in trades or books. Work becomes a necessity to him. The only punishment is a dark cell with deprivation of work for a period. The New York system is as has been practiced at Auburn, by which the prisoners are confined in solitary cells during the night, but have companionship during the day while at work, and at the dinner table. Each system has warm advocates. The solitary cell system has had most practice in Europe but the American plan has made up the lack of proper classification by the excessive work of prisoners. Many persons hold that classification of prisoners in groups is a failure, and that the solitary cellular system is the only commendable method. Edward Livingston has thus set forth the advantages of this system: “Every association of convicts that can be formed will, in a greater or less degree, corrupt, but will never reform those of which it is composed, and we are brought to the irresistible conclusion that classification once admitted to be useful, it is so in an inverse proportion to the numbers of which each class is composed. But it is not perfect until we come to the plan at which it loses its name and nature in the complete separation of individuals. We come then to the conclusion that each convict is to be separated from his fellows.”[4] The extent of isolation which each prisoner undergoes must be determined somewhat by the nature of his case and somewhat by the conditions and convenience of the prison. It is hardly possible for many modern prisons to have complete separation on account of the expense incurred, for this would mean that within the cell itself the prisoner must perform all labor, and that the cell shall be commodious enough to carry on this labor by himself, or else that he be given labor elsewhere alone. Such a system requires an increased amount of attendance.