Improvement has also lagged in the matter of coupling cars. It has been shown by statistics and calculations that some hundreds of persons are killed and some thousands injured in this country annually in coupling cars. The use of automatic coupling, by which cars could be connected together without going between them, it has been supposed, would greatly lessen, if it would not entirely prevent, this fearful sacrifice of life and limb. To accomplish this end, though, it is essential that some one form of coupler shall be generally adopted by all railroads. One of the obstacles in the way of this has been the mechanical difficulty of finding a mechanism which will satisfactorily accomplish the purpose for which it was intended. After thirty or forty years of invention and experiment, no automatic coupler has been produced, which has been approved by competent judges with a sufficient degree of unanimity to justify its general adoption. The patents on that class of inventions are numbered by thousands, so that it is no light task to select the best one or even the best kind. Besides this difficulty, there is the other equally formidable one of inducing railroad men, of various degrees of knowledge, ignorance, and prejudice regarding this subject, and who are scattered all over the continent, to agree in adopting some one form or kind of automatic coupler. Various cliques had also been organized on different roads in the interest of some patents, and in such cases argument and reason addressed to them were generally wasted. Public indignation was, however, aroused; and the stimulus of legislation in different States compelled railroad officers to give serious attention to the subject. After devoting some years to the investigation, the Master Car-Builders' Association--which is composed of officers of railroad companies, who are in charge of the construction and repair of cars on the different lines--has recommended the adoption of a coupler of the type represented by Figures 47 to 49, which has been already applied to many cars and the indications are that it will be very generally adopted for freight and probably for passenger cars. If it should be, it will relieve railroad employees of the dangerous duty of going between cars to couple them. Figure 47 shows a plan looking down on the couplers with one of the latches, _A_, open; Figure 48 shows it with the two couplers partly engaged; and Figure 49 shows them when the coupling is completed. [Illustration: Fig. 45.--Old Car for Carrying Firewood on the Baltimore & Ohio Railroad.] [Illustration: Fig. 46.--Old Car on the Quincy Granite Railroad.] One of the first problems which presented itself in the infancy of railroads was how to keep the cars on the rails.