With these shortcomings in mind, the automatic air brake was produced in 1873, in which the method was reversed. With the addition of an auxiliary reservoir under each passenger car and a triple valve, application of brakes was secured by reducing the train-line pressure, while admitting air from the main reservoir raised the pressure and released the brakes. On the application of the automatic air brake to freight cars it was found the reduction of pressure was not quick enough to set the rear brakes promptly, and in consequence accidents occurred from the bunching of the cars. The consideration of the brake question by the Master Car Builders' Association in 1885, and public tests under their auspices in 1886, at which time the manufacturers were represented, did not succeed in stopping freight trains without violent and disastrous shocks. So discouraging did these tests seem for the time being, that a report was made, suggesting that the successful application of such brakes on long trains could only be accomplished by electricity. However, the following January witnessed the introduction of the Westinghouse Quick-Action air brake, which corrected the previous trouble and made practicable the application of air brakes to long freight trains. Continuing from this time there has been marked improvement and development in all features of the apparatus, without, however, modifying the essential elements of which it is constituted. With the solution of a means of train control came a further growth in their size and weight; sooner or later this had to emphasize the necessity for efficient coupling devices. Not only were there accidents due to the primitive link and pin couplers, but the various standards in existence both complicated the operations of coupling and uncoupling of cars and involved the question of interchange and safety. AUTOMATIC COUPLERS.