The difficulties, dangers, and expense of mail transportation over this route are not comparable with the Panama route, as it formerly was, or even as it now is, as to the 17 miles yet uncovered by railroad; and this company confidently believe that they will be able to carry the mails over this route for a sum 50 per cent. per mile less than by the Panama route, and in a time under three days. The company have placed a portion of their rolling stock upon the road, at present equal to the transportation of fifty passengers per week from ocean to ocean. This rolling stock consists of the very best built Albany and Troy post-coaches, Concord (New Hampshire) passenger, baggage, express and specie wagons, and about 500 horses and mules, (at the last report 493.) It is hoped the next advices from Colonel Ramsey will give information that this rolling stock is in operation. It is intended to increase the rolling stock with the increase of travel. The local travel and business in Mexico will alone pay a large interest on the investment; and were there no connexion with steamers on either side, and as a mere stage route, the profits will be large, especially when that portion of the route through the State of Guerrero is properly worked and widened, and over a portion of the route the company hold the exclusive right of passage, ferries, tolls, &c., for fifty years. This company apprehend no difficulty in transporting any mails on account of the weight, inasmuch as the company will be prepared to transport the English mails, between England and Australia, in under 47 days; and those mails, it is said, weigh 11 and 12 tons. The remarkable feature in this route is, that it passes through a constant succession of cities, villages, ranches, &c., (few scarce ten miles apart,) and through a population as dense as might have been found on the old turnpike mail road from Albany to Buffalo before the age of railroads, or on any of the great leading mail routes of New York and Pennsylvania of a ratable distance; and the annexed itinerary, taken from official Mexican documents, verifies the position. Fears have been expressed that robberies might endanger the mail, passengers, or property. This difficulty has been wondrously magnified, and is provided against, as the vehicles of this company are all armed with blunderbusses and revolvers; and small, but strong, light, iron boxes for specie, jewelry, and valuables, are securely attached as fixtures in each coach. The material fact, however, on this point is, that this line of route is seldom visited by robbers, owing to the more peaceful, permanent, and dense character of the population, and the consequent exposure to detection. General Santa Ana has, moreover, made a decree that the inhabitants of each district shall be responsible for the damages by such depredations.