A Lange 1815 Rattrapante Perpetual Calendar, In Platinum

For a high end, haute horlogerie watchmaker to show a complete mastery of the craft, there are certain complications which it’s necessary to produce to a level commensurate with the company’s reputation. These complications include the classic three high complications: the minute repeater, the perpetual calendar, and the rattrapante chronograph. (If you have all three in one watch, you have a watch which fits the traditional definition of a “grand complication” although the user of the term has become a bit more elastic these days).

Lange has since its relaunch in 1994 demonstrated its ability to make watches using all of these complications and more (its magnum opus in terms of sheer complexity is the 2013 Grand Complication, which incorporates a grande et petite sonnerie, minute repeater, instantaneous perpetual calendar with moonphase, and rattrapante chronograph with foudroyante seconds) but that same year, Lange introduced a watch which, while less complicated, was perhaps a bit more practical for daily wear, and which was in its own right a tour de force of complicated watchmaking. That watch is the watch we have today for A Watch A Week: the l815 Rattrapante Perpetual Calendar.

The 1815 Rattrapante Perpetual is a watch built along classic Lange lines. It’s extremely solidly built; while it undeniable looks and feels exceptionally luxurious, especially in its 41.9mm x 14.7mm platinum case (Lange platinum cases always seem to have twice as much platinum as most other company’s platinum cases; they absolutely radiate quietly confident affluence) the impression you get of having, in the hand and on the wrist, a remarkably well engineered object is just as strong. While there are no obvious attempts at attention getting flourishes, there is also a flawless execution of all of the details of the case, crown, pushers, hands, and other aspects of the externals for which Lange has been famous for its entire history (both pre and post German re-unification).

Today there are a quite wide range of ways to organize a perpetual calendar display These range from exercises in severe minimalism to ingenious variations on the theme, but the 1815 Rattrapante Perpetual like its sibling the Grand Comp, takes its cues from the no. 42500 grand comp pocket watch on which both were based. The 1815 Rattrapante Perpetual shows two displays in each subdial: at 12:00, the chronograph minute counter and power reserve; at 3:00, the Leap Year cycle and the current month; at 6:00, the moonphase and running seconds; and at 9:00, the day of the week and the month. Chronograph seconds as is normal for any chronograph, are on the center axis of the dial along with the hour and minute hands and in the 1815 Rattrapante Perpetual, they’re joined by the second, split-time hand.

Although it occasionally happens in traditionally configured perpetual calendars, that the 31 and 1 feel a bit crowded together, this is not the case in the 1815 Rattrapante Chronograph; the subdial is divided into equally sized sectors and the 1 is set off by its red color from the rest of the numbers.

The 122 year moonphase is shown in an absolutely traditional way as well, with the white gold moon disk perfectly polished on its upper surface. The hands of the 1815 Rattrapante Perpetual are very finely finished as well, although the chronograph seconds and split hands are especially notable. They’re hair-fine and as is necessary in a well made rattrapante, adjusted so that they are perfectly superimposed when they are running together, so that it appears that there’s only one hand, not two.

The movement is caliber L.101.1 and like all complicated Lange movements, it has a three-dimensionality that sets it well apart from other complicated watches.

The movement follows the traditional playbook for the organization of the complications, with the perpetual calendar works hidden under the dial, and the rattrapante chronograph components, including the double column wheels necessary for a classic rattrapante, visible from the back. The column wheel nearest the crown coordinates stop, start, and reset of the chronograph, and the other is responsible for the split function, which is activated by the pusher at 10:00 (as seen from the dial side).

Here’s how it works: when you push the split button, the split column wheel (the lower of the two in the image) is drawn around clockwise by the curved lever and its pivoted pawl extending outward from the jeweled chaton on the far right. This causes the two jaws of a clamp to fall onto the outer edges of the rattrapante wheel. This visible upper wheel carries the pivot of one of the two chronograph hands and when it’s locked by the clamp, it stops, while the other hand continues to run.

The running hand has on its pivot, a heart-shaped cam identical to those used in a chronograph for return-to-zero. This cam rotates along with the running seconds hand, so it’s always rotating as long as the chronograph is running. Inside the upper rattrapante wheel (for the split hand) there is a pivoting, spring loaded lever tipped with a ruby hammer. If both hands are running, the pressure of this hammer on the heart cam fixes the split hand in the same position as the running chronograph seconds hand. When the hands are split, however, the cam continues to rotate, while the hammer presses on it. Once the split pusher is pressed again, the jaws of the clamp open, and under the pressure of its spring, the hammer rotates the heart cam until the hammer is once again resting on the lowest part of the cam, which rotates the split hand back into the same position as the chronograph seconds hand.

Here’s how the system looks in the 1815 Rattrapante.

In a more traditionally constructed rattrapante chronograph, the ruby hammer’s replaced by a ruby roller on the tip of a lever with a very thin blade spring pressing it against the heart cam. The Lange rattrapante’s based on the same principle but is designed for greater simplicity and durability, although at the expense of slightly increased friction on the heart cam.

Both visually and from an engineering and watchmaking standpoint, this feels like a very German and very Lange watch (although those who adhere to the notion of German engineering being a bit too much in love with complexity for its own sake, might feel that the simplicity and robustness of Lange’s version of the rattrapante is the opposite of typical German engineering!) Ultimately, though, the watch stands on its own identity as one of the most complex watches Lange’s ever made, and one which shows why and how the traditional approach still gives timeless results.

The Lange 1815 Rattrapante Perpetual ref. 421.025FE: case, platinum, 41.9mm x 14.7mm, 30 meter water resistance, sapphire crystals front and back. Movement, Lange caliber L101.1, hand wound, with 42 hour power reserve, running at 21,600 vph. Perpetual calendar with moon phase and rattrapante chronograph function. View the 1815 Rattrapante Perpetual Calendar here.