Notwithstanding the thought expended and the ingenuity displayed by the inventors of our country toward the improvement of railroad cars, with a view of better adapting them to the comfort of the traveling community, there yet remain two objects for them to accomplish which are not only desirable to companies and travelers, but which are sure to bring to the inventor who is fortunate enough to successfully produce them a handsome income. We allude to some system by which convenient and simple sleeping couches qan be providedfornighttravel, and readily converted into ordinary seats during the day, and some contrivance for ventilating the cars, without admitting the clouds of dust that necessarily enter the cars when the windows are raised or opened. These subjects have occupied the minds of many inventors for some time, and for several years past statements have gone the rounds of the press in praise of what -SKfirc erroneously termed improvements for effecting both objects. The efforts of the numerous inventors whose attention they have occupied have not produced the desired effect in a satisfactory manner, although good has resulted from their labors. A f ew ye ars ago a prize was offered f or the best sleeping car by the late F. M. Ray, of this city, but among those exhibited there was not one which was deemed entitled to it. In this country where we measure distance by thousands of miles, and think no more of a trip by rail from New York to St. Louis, nearly two thousand miles, than they think in Europe of a trip from London to Paris, about three hundred miles, it is with many persons an absolute necessity that the railroad companies should provide them with sleeping accommodations for the night, and in consequence we learn from the letters of our correspondents that there is at present quite an interest among inventors to produce & really good and convenient sleeping car. We understand that a western railroad company have agreed to give one cent per mile for the use of an approved arrangement of sleeping couches on every car on their road to which it may be applied. This would y.ield an income to the successful inventor of $1,000 per annum for each car, and as the road employs forty cars, would ensure to the inventor for the single road a tariff of $40,000 per annum. Railroad companies would be justified in paying a liberal sum for the use of inventions for accomplishing these objects in the satisfactory manner desired, for the increase of travel that would follow their adoption would produce an extraordinary increase in the annual receipts of the company. In case that any of our readers should wish to try their inventive powers on this subject, we will give them the points that are desirable to be remembered in the production of the present desideratum. The car must be simple in its construction, and the seats be capable of reversing as at present, and should be able to accommodate as many sleeping as sitting down; the less shelving the better, and strength combined with lightness are points to be recollected, and above all, rapidity of adjustment either from seats to beds, or vice verta, should be the end to be attained. We have applied for patents for several improvements, but there is still room for further inventions on what are termed "sleeping cars," and we hope inventors will exert their energies in that line until the same facilities are offered for night traveling on railroads as are obtained on our river steamboats. Give us easy seats by day, and convert the seats into a state-room at night, and railroad traveling will then have reached a state oi ! perfection in this country that will make ^ American railroads far beyond those of any ^ other country.