The #7 astronomical regulator has a half seconds pendulum, with the flat bar grid iron temperature compensation. This pendulum differs from the ones on my previous regulators in that it has brass cross bars, to provide additional compensation. It is driven by a two pound weight with a weight drop of 12.5 inches for eight days. The movement is mounted on a white marble base and backboard for stability. The base is drilled to receive the weight, but the weight stays above the hole, except if the clock runs the eighth day. The clock has a pull wind mechanism to keep the case from being opened and letting dirt in on a weekly basis. The small counterweight on the left pulls the winding cord back into the case.
This dial view shows the blue steel hands on the matte sterling silver dials. The dials are set into recesses into what would ordinarily be the front plate of the movement. The edge of this plate, which I call the uniblock, is engine turned to form a bezel. The visible escapement is covered by a watch glass inserted in the hole in the seconds bit, and drilled to receive the seconds hand arbor. The escapement recess, which is very shallow, is backed with a silver disk to match the dial. The 'scape wheel is spring steel, .015" (.4 mm) thick. It has sixty teeth, with angled tips, to split impulse between the pallet stones and the scape wheel. The backs of the teeth are curved, as in a club tooth lever escapement in a watch, to provide back clearance for the corner of the pallet. In this way, the drop can be kept to a minimum. The verge is made of .032 spring steel. The escapement uses watch pallet stones. The pendulum maintains an amplitude of about a quarter of an inch.
The uniblock construction is based upon the Lepine caliper in watches. This back view shows the layout of the train. The large and tall bridge to the right holds the barrel and great wheel assembly. The maintaining power ratchet has crossings which match the great wheel, and when it is running with the maintaining spring bottomed out, the crossings align with each other. The winding click engages the teeth of the winding gear. The maintaining power pawl runs on a shoulder screw, and is concealed behind this bridge. This bridge is as tall as it is to move the weight to the rear, behind the pendulum. All the power transmitting arbors run in jewels, and endstones are used in all pivot points except the front of the center and 'scape arbors. At the top of the plate is a pivot block which holds the rear pivot of the 'scape arbor, at the bottom one which holds the verge arbor. The crutch is mounted horizontally and bears down upon a jewel mounted on the side of the pendulum. The set screw is used for setting the beat, and ends is a point with a small, polished radius. By placing the crutch at right angles to the pivot point, the small tendency of any knife edge suspension to "walk" will not knock the clock out of beat causing it to stop. The center and third wheels share a bridge, as do the two wheels of the cadrature. The center wheel is mounted to a collet which is staked to a hollow pinion. This is secured to the center arbor with a hand setting tension spring. The center arbor is cut with the cannon pinion. The entire length of the center arbor assembly is about 3/4 of an inch. The winding mechanism is visible on a lever at lower right. It is mounted on a pivoted arm which disengages from the winding gear when not in use.
This side view shows the general thinness of the movement. Both the uniblock and the two bridges are 3/8 of an inch thick. The uniblock fits on two lancet fittings, one on the post at the top, and the other on the bottom plate. It is secured to the mounting plate with a knurled screw which threads into the bottom block which forms the great wheel bridge. The turning pulley is visible at the top. Is matches the barrel and is threaded, not only to help the cord to track correctly, but to assure that the weight travels backward as it descends and provides clearance to the pendulum bob.
The marble backboard is beveled on both sides, and grooves in the rear channels of the vitrine fit over it . Since the backboard is tapered at a two degree angle, the vitrine only has to be lifted half way off to remove it. The base has knurled leveling feet, which are gilded to match the other visible brass elements.
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