_Faults of the L camera._ The L camera was the mainstay of the English Air Service. In fact for the last two years of the war it was practically the only camera the English used, and they thought highly of it. It is, of course, subject to the limitation of small plate size and short focus lens. It is in many ways an inconvenient camera to handle. For instance, the upper magazine cannot be closed or removed until all the plates are passed through. Its dependence upon gravity for the plate changing operation is a fundamental weakness, responsible for its frequent tendency to jam in the air. Experience made the English observers very expert in relieving these jams. Sometimes they would turn the propeller backward (mounting it in an accessible position to provide for this contingency), sometimes they would shake or thump the camera. But while these makeshifts would serve to secure pictures—the chief object, of course, of the photographic service—they can scarcely be said to render the camera satisfactory. Moreover, the propeller drive has not been universally approved, as it furnishes an additional mechanism to make trouble. Since it is not feasible to change from power to hand operation while in the air, the camera is put out of commission whenever the propeller or shaft is disabled. Bowden-wire controls for both plate changing lever and shutter release were common in the British service, which considered the extra operation or the extra muscular exertion unimportant when compared with the greater assurance of reliable action. =The English LB and BM Cameras.=—During the closing months of the war an improved L type camera was constructed, the LB. This differs from the L in a number of detail changes, dictated by experience. The shutter is now made removable and self-capping. Pivoted lugs are provided to hold the exposed plate horizontal until the very instant it drops, in an effort to prevent jams caused by the plates piling up at an angle in the receiving magazine. The chief addition, however, is the provision of several interchangeable cones and cylinders, for carrying lenses of focal lengths from 4 to 20 inches. Fig. 95 shows the LB with 20 inch lens cylinder mounted on a bell crank support in the camera bay of an English plane. The BM camera is but a larger edition of the LB, for 18 × 24 centimeter plates. It also carries several interchangeable lens cones.