Particular attention is solicited to that portion of the report of the Postmaster-General which relates to the carriage of the mails of the United States upon railroads constructed by private corporations under the authority of the several States. The reliance which the General Government can place on those roads as a means of carrying on its operations and the principles on which the use of them is to be obtained can not too soon be considered and settled. Already does the spirit of monopoly begin to exhibit its natural propensities in attempts to exact from the public, for services which it supposes can not be obtained on other terms, the most extravagant compensation. If these claims be persisted in, the question may arise whether a combination of citizens, acting under charters of incorporation from the States, can, by a direct refusal or the demand of an exorbitant price, exclude the United States from the use of the established channels of communication between the different sections of the country, and whether the United States can not, without transcending their constitutional powers, secure to the Post-Office Department the use of those roads by an act of Congress which shall provide within itself some equitable mode of adjusting the amount of compensation. To obviate, if possible, the necessity of considering this question, it is suggested whether it be not expedient to fix by law the amounts which shall be offered to railroad companies for the conveyance of the mails, graduated according to their average weight, to be ascertained and declared by the Postmaster-General. It is probable that a liberal proposition of that sort would be accepted.