Governor LINCOLN, of Massachusetts, in a late message, recommended, that immediate provision be made for the erection, as soon as may be, in the prison yard, of a building, with sufficient cells for the separate confinement of the present, and any future probable number of convicts. Governor WOLCOTT, of Connecticut, stated to the Legislature, in May, with reference to the improvements at Auburn, that there were few subjects upon which their deliberations could be bestowed with higher advantage to the best interests of the State. Governor CLINTON has formerly expressed his opinion of the importance of solitary confinement, and in his late message to the Legislature, he expresses an opinion concerning the institution in New York city, for the reformation of Juvenile Delinquents, which is constructed on the plan of the building at Auburn, that it is probably the best Prison in the world. Judge WOODBURY, of New Hampshire, says, that 'Prisoners, during the night, should be wholly separated from each other.' Mr. HOPKINTON, of New Hampshire, says, 'a novice, who, if kept from company worse than himself, might have been reclaimed from his first attempts, is here associated with old, hardened, and skilful offenders; he hears with envy and admiration the stories of their prowess and dexterity; his ambition is roused; his knowledge extended by these recitals; and every idea of repentance is scorned; every emotion of virtue extinguished.' Judge THACHER, of Boston, says, 'by the confession of those who administer our Penitentiaries, it is found, that most of the evils of this system of punishment flow from the almost free and unrestrained intercourse, which subsists among the convicts.' THOMAS EDDY, of New York, says, 'if a number of ingenious men were requested to suggest the best possible mode of increasing the number of thieves, robbers, and vagabonds, it could scarcely be in their power, to fix on any plan, so likely to produce this effect, as confining in one collection, a number of persons already convicted of committing crimes of every description.' Hon. EDWARD LIVINGSTON, says, 'it is a great point to produce the conviction of the important and obvious truth, denied only by a false economy, that Prisons, where there is not a complete separation of their inhabitants, are seminaries of vice, not schools for reformation, nor even places of punishment.' ROBERTS VAUX, of Philadelphia, lays down five fundamental principles of Prison Discipline, the _first_ of which is, 'that convicts should be rigidly confined to solitary life.' There is no disagreement between the opinion of these distinguished individuals, and the opinions of various commissioners, directors, &c. who have written on this subject.