“A Maine Yankee” announces through the “National Intelligencer,” the invention of a form of road and improved locomotive, which, he says, will safely transport the mails and passengers at the rate of one hundred miles per hour ! The writer further says he has been made acquainted with the details of these improvements," which are so palpably correct in theory, and feasible in practice, that every civil engineer and railroad man will, on examination, at once recognize them as the desideratum, even to the extent of safety and speed above indicated." The next Congress, it is said is to be invited to secure its adoption, and give to the world the result of the first experiment.— [Exchange. [Let us know the plan and then we can form some opinion of its correctness. It may be good and may be perfectly futile. We would state that 100 miles per hour have been run by a locomotive already.