Nothing is more obvious than that from the very nature of the discipline, the administration of a prison on the separate plan must be the least expensive. The first cost of the structure will probably be greater; but we have supposed it to be conceded on all hands, that a prison on this plan once erected, the expenses of maintaining it were much less than those of a congregate prison with equal accommodations. While we admit that the first cost of a prison for convict-separation is greater than that of a congregate prison, we must demur to the Rev. Commissioner's broad assertion on this point: "I speak not unadvisedly," he says, "when I assert, that the erection of a prison for associate purposes, is not half so expensive, as the erection of a prison for the separate and solitary confinement of its inmates--all things considered." The most zealous opposers of the separate system have not pushed this objection to any such extreme, and to any considerate mind it carries its refutation with it. As an inducement to proceed on the plan submitted by the commissioner, he assures the executive that "the prison once completed and properly officered, unless in case of some unforeseen accident, will demand of the State treasury nothing more for at least fifty years! And more than that," he says, "after paying for itself during the first few years of its existence, it will thenceforth yield annually a handsome revenue to the State." The cost of the Missouri "Model Prison" is set down at $250,000, and as a sort of guaranty against any new expense for improvement in after times, the commissioner has the assurance of one gentleman, (which another promptly endorses,) that "the principles of the main building are such as will last for one hundred years!" This gives a chance for a long nap to our Boston friends. We are not without hope that some of the good citizens of Missouri will get a glimpse of this report of the Rev. Alexander L. Hamilton, and will insist upon a more intelligent and impartial inquiry, before they commit themselves, or suffer the Legislature to commit itself to so large an expenditure, for an institution so permanent, and involving so many interests of humanity and public economy. ART. VIII.--A PHILANTHROPIC PERPLEXITY. Will the publishers of the _Prison Journal_, or some one who has access to its columns enlighten an honest inquirer after the path of duty? It is presumed that the combined wisdom and philanthropy of the Prison Society can furnish all needed direction in the case I have at heart and in hand.