Elevated railways have been in operation for a long time in New York, Berlin, and Vienna, and the city of Paris has decided to have recourse to this mode of carriage, so indispensable to large cities. The question of establishing a line of railways in our capital has been open, as well known, since 1871. During this period of nearly fourteen years this grave subject has at various times given rise to serious discussions, in which the most competent engineers have taken part, and numerous projects relating to the solution that it calls for have been put forth. The problem to be solved is of the most complex nature, and the engineers who have studied it have not been able to come to an agreement except as regards a small number of points. It may even be said that unanimity exists upon but a single point, and that is that the means of locomotion in Paris do not answer the requirements of the public, and that there is an urgent necessity for new ones. The capital question, that of knowing whether the railway to be built shall be beneath or above ground, is not yet settled; for, up to the present, no project has been prescribed in one direction or the other. While some extol the underground solution as being the only one that, without interfering with circulation in the streets, permits of establishing a double-track railway capable of giving passage to ordinary rolling stock and of connecting directly with the large lines, others, objecting that such a road could not give satisfaction to the taste of Parisians, and that it would necessitate work out of proportion to the advantages gained, conclude upon the adoption of an open air railway. Preferences generally are evidently for this latter solution. We have received from a learned engineer, Mr. Jules Garnier, a project for an elevated railway, which appears to us to be very ably conceived, very well studied out, and which we hasten to make known. (1.) The system is characterized by the following fundamental points: The up and down tracks, instead of being laid alongside of each other, as in an ordinary railway, are superposed upon two distinct platforms forming a viaduct, which is consequently so arranged as to permit of the laying of one of the tracks at its lower part and of the other at its upper. (2.) The system of constructing the viaduct is so combined as to be capable of giving passage upon the road to the rolling stock of the large lines during the stoppage of the daily passenger trains. (3.) The tracks are connected at the extremities by a curve that has the proper incline to compensate for the difference in level between the two, and which has a sufficiently large radius to allow the slope of the track to be kept within the limits admitted. The running of the trains is thus uninterrupted.