As long as the Mont Cenis Railway is the only railway open towards the western extremity of the Alps, France may refuse to agree to such an arrangement. There would then be no alternative but to continue the heavy mail service _viâ_ Southampton, until the completion of the Simplon Railway would make both England and Italy independent of France. The reason is, that there would then be two routes between England and Italy, _viâ_ the Simplon; one, undoubtedly the shorter, through Paris, Dijon, Pontarlier, and Lausanne, the other through Ostend, Belgium, Rhenish Germany, and Switzerland. The distance from London to Brindisi, _viâ_ Paris, Dijon, &c., would be 2,395 kilometers; _viâ_ Ostend, Belgium, and Rhenish Germany, 2,758 kilometers. At the present time the fast mails are conveyed between London and Alexandria, _viâ_ Marseilles, in 193 hours, or eight days one hour. According to the calculations of Captain Tyler, the fast mails can be conveyed from London to Brindisi, _viâ_ Mont Cenis, in sixty-nine hours. That is to say, a letter posted in London on the evening of the 11th of a month would arrive in Brindisi at 5·30 p.m. on the evening of the 14th; allowing two hours for placing the mails on board the steamer, she would start at 7·30 p.m., and at the existing contract rate of ten knots an hour, she would reach Alexandria in eighty-three hours; that is at 6·30 a.m. on the 18th. If the Simplon line were opened, the mails would be conveyed in, at least, three hours less time; making the arrival at Brindisi 3·30 a.m. Thus, the total distance would be accomplished in 151 hours, or six days seven hours; showing a saving over the Marseilles route of forty-two hours. If the French Government would enter into an agreement for carrying the HEAVY MAILS, through French territory _by ordinary trains_, they could be conveyed between London and Alexandria in seven days nineteen hours; or six hours less time than at present, _viâ_ Marseilles: in other words, these mails need not be despatched from London until thirty-six hours before the departure of the fast mails. But if the adoption of the route, _viâ_ Ostend, Belgium, and Rhenish Germany, be unavoidable, it will then be necessary to despatch the heavy mails twenty-four hours earlier than if they were transmitted _viâ_ France. Still this despatch will only be two days and a half earlier than the despatch of the fast mails, instead of being eight or nine days, which would be the case if the heavy mails still continued to be despatched _viâ_ Southampton.