Prominent among the older type of air-checks is the _Eclipse_ made by Sargent & Co. This check is clearly illustrated in Fig. 117. At (_a_) and (_b_) are shown two methods of applying the _Eclipse_ air-checks. In (_a_), the spring-check that closes the door is shown at _a_ attached to the door, while its lever-arm is fastened to the door casing. The cylinder _b_ is also secured to the door, and the piston _c_, operating in the cylinder, is applied to the door casing. At (_b_), the parts are differently arranged. The spring-check occupies the same relative position as shown in (_a_), its lever-arm being shown at _a_, while the piston _c_ is fastened to the door and the cylinder _b_ affixed to the head-jamb of the door frame. Either method is adapted for inside doors, but that shown at (_b_) is preferable for doors opening outwards, on account of fewer parts being exposed; the spring-check and its lever-arms, in this case, being the only parts exposed to the weather. In construction these checks consist of a cylinder _b_ with a polished interior, in which works the piston _c_. On the end of the piston there is provided a cup made of leather that has previously been soaked in oil. By the insertion of the piston into the cylinder as the door closes, there is a tendency to compress the air in the cylinder, thus forming an air cushion with air outlet at the caps. These outlets can be regulated by turning, or screwing, the cap to the right or the left, as the case may require. [Illustration: FIG. 116] [Illustration: FIG. 117] Devices of this kind, however, did not prove satisfactory until the introduction of the _Yale-Blount_, or _hydraulic, combined_ _spring and check_, which is shown in Fig. 118. In this device, the coil spring _a_, shown in (_b_), is enclosed in the vertical portion of the check, the regulating of the tension being accomplished by turning the ratchet sleeve _b_ with a wrench made for that purpose. The check enclosed in the horizontal part consists of a metallic piston _c_, without packing, that moves in a tightly sealed metallic cylinder containing a lubricating and non-freezing liquid. The movement of the door in closing depends on the escape of the liquid through a by-pass from one end of the cylinder to the center, this by-pass being controlled by a small valve that may be readily adjusted to produce any desired action of the door and thus permit the door to be closed silently, with a smooth, steady motion, and without rebound. Since the introduction of the Yale-Blount type of check and spring combined, other manufacturers are making similar styles, the most prominent being the _Bardsley_, the _Corbin_, the _Sargent_, and the _Ogden_. [Illustration: FIG. 118]