Perhaps not the most elegant design of a lathe intended for use by a watchmaker, the efforts of Frederik Shaller were concerned with improving the ability to clamp work securely and on centre and also claiming the benefits of: "...an adjustable gauge and reversible male and female centring-pin." Like those proposed by other inventers in the 1800s, including Jackson, St. John, Hopkins and Kesselmeir, it was not a quick and truly automatic system and did require the operator to somewhat manipulate the assembly in order to achieve the desired  alignment.
At a time when many jobs had to held in place by wax, the advantage of the simple clamping device (Fig.2) mounted on what the patentee called a chuck (E) - today described as a small-diameter faceplate - is easily understood. Two clamping bars were provided (E and F) pivoting around the points (b) each positioned the same distance from the spindle centre line and able to be brought together by the screws (d). The result was that any round job held between the bars would have been automatically centered and held fast. Unfortunately, it has not be possible to find the take-up of this device by any maker of watch lathes - though perhaps it might resemble in some way the "ferrules" shown here.
The description of the "double-spindle" tailstock (H) is less clear, though cutting through the usual convoluted language used in patents, it seems that (I) is a typical centre (or runner) though with one end male and the other female, while (J) is a sliding bat that ends in a "slotted plate and tool guide" (g) to act as a depth-stop when turning using the hand T-rest (G). In the patent's flowery language of the patent this becomes: "For delicate work, this gauge and the reversible male and female centring-pin in the one poppet [tailstock]will be found very convenient, and save much time and labor. The turning of the work to a fixed gauge, acting as a guide to the tool, as is the case here, not merely expedites performance of the work and insures accuracy, but also avoids much stooping and straining of the eyes.."