The whole extent, then, of the French lines of telegraph is 1,474 miles, with 519 stations; and (if the estimate for six stations, at an average cost of 4,400 francs, is a criterion for the rest) erected at a cost of at least $880 each—making a total of $456,720. The electro magnetic telegraph, at the rate proposed in the bill, to wit, $461 per mile, (and which, it should be remembered, will construct not _one_ line, only, but _six_,) could be constructed the same distance for $619,514—not one-third more than the cost of the French telegraphs. Even supposing each line to be only as efficient as the French telegraph, still there would be six times the facilities, for not one-third more cost. But when it is considered that the French telegraph, like the English, is unavailable the greater part of the time, the advantages in favour of the magnetic telegraph become more obvious. An important difference between the two systems is, that the foreign telegraphs are all a burden upon the treasury of their respective countries; while the magnetic telegraph proposes, and is alone capable of sustaining itself and of producing a revenue. Another difference in the two systems is, that the stations in the foreign telegraphs must be within sight of each other: a fact which bears essentially on the cost of maintenance. The French telegraph requires for the distance of 1,474 miles, no less than 519 stations—averaging _one for about every three miles_. The number of stations of the magnetic telegraph, on the contrary, is optional. The two stations (one only at Baltimore, and one at Washington) show that they may be at least 40 miles apart; and there is no reason to doubt, from experiments I have made, that 100 miles, or even 500 miles, would give the same results. In the maintenance, therefore, of stations, the magnetic telegraph would require but 15 stations, (assuming that 100 miles is the _utmost limit_ of transmission between two stations which is not probable;) while the French requires 519 for the same distance. When to this are added the facts that the magnetic telegraph is at _all times available_, at _every hour of the day or night, irrespective of weather_; that, in comparison with the visual telegraphs, it communicates _more than a hundred-fold_ the quantity of intelligence in the same time; that it is originally constructed at a _less cost_, (_all things considered;_) that it is _maintained for less_; and that it is capable, by a rate of charges for transmitting intelligence, not only of defraying all its expenses, but, if desired, of producing a revenue, I may be permitted to hope that when these great advantages are fully understood, my system will receive that attention from the government which its intrinsic public importance demands.