Hi everyone. With this post I want to present the last clock I've done, it's "El Primero" (the first). Of course it's not a Zenith watch, is the very first pendulum clock ever built. This clock was conceived by Christiaan Huygens, a prominent Dutch mathematician and scientist born in the Hague (Dutch Republic). Huygens through mathematical calculations determined that, for an accurate clock, his pendulum should follow a cycloidal path in its oscillations and not circular one. The later is what happens when a pendulum is suspended to a fixed point without any other mechanical contrivance. As a consequence of this "circular swing" of the pendulum, circular error comes. In other words the time of the swing varies in proportion to it's arc (no iso-cronyism). In a clock with a fixed point anchored suspension, when the power applied to train descends, the pendulum`s swing angle descends too. This results that as the energy of the spring decreases over time, the clock varies his rate in the same proportion. This effect is more exaggerated in spring driven clocks rather than in weight driven ones. But in the laters also occurs, since the uneven transmission of energy from the barrel To escape due to imperfections in the gears, also causes loss of isochronyism, and thus loss of accuracy. To force the suspension to follow the cycloidal path, Huygens developed a system that consisted of a pair of folded sheets called "cycloidal cheeks" of which hung the silk thread pendulum suspension. The curved cheeks shorten the length of the pendulum and counter circular error. In this way, is achieved that the suspension becomes "isochronous". In other words, the period of the pendulum is not dependent on the angle of oscillation. Without doubt there is a mathematical explanation for all this matters, but that is not scope of this post. Huygens was a very versatile man. He was mathematician, scientist, astronomer, physicist, horologist and probabilist, but not clockmaker (may not be all perfect). So to carry out his invention he needed a craftsman who built it. He made a prototype by the end of 1656 and in 1657 he contracted the construction of his designs to Salomon Coster a Dutch clockmaker of the Hague, who in this year, was the first clockmaker to make a pendulum clock. From this moment such watches are known as "Coster clock", and at present all of theese clocks manufactured under Huygen`s license are in museums (the oldest known Huygens-style pendulum clock is dated 1657 and can be seen at the Museum Boerhaave in Leiden) or in private collections. Back to the present I would like to comment my experience in the construction of this singular clock. I followed the plans made by C.J. Thorne LBHI and available on the web. I have made changes in what in my judgment improved the aesthetic of the clock. Of course this is questionable. I'm not versed in the construction of such types of clocks, in fact is the first time I do one whith crown and verge. The first thing that surprised me is the amount of energy they need these types of escapes. Barrel size is fairly large, and the mainspring that corresponds to it is the largest available in the standard supplies. As be imagined, the force that must be performed in order to winding the clock is considerable. In this clock everything is strong and oversized. Some time ago I restore a half-second pendulum clock of the type "Vienna Regulator" with shafts pivots of the leg size of a mosquito, this clock is located on the opposite side in terms of mechanical concept. You could say that this is a "muscle clock". The verge (pallets and arbor) is by far, the hardest part of making from all the clock and I suspect that is not properly designed, according to plans. I'll explain. When the clock is in running order, the "tic" corresponding to the palette with short arbor to pivot, rings loud and clear, but he "tac" of the palet in the side of the cruth bounces. It sounds like "trrrac", soft but appreciably. I'm not sure if there is a problem of lack of diameter in the arbor or that, it is too hardened, or simply that in such clocks this is normal. I would appreciate any comments about this. The back plate engravings are handmade and are a personal contribution as well as the cycloidal cheeks potences, which simulate the wings of a dragonfly. The brand signature is made with pantograph. Make letters engraved by hand is extremely difficult, at least for me. Regarding its performance is early to draw conclusions, but at first glance, it seems that is far from being a regulator, although it was a major advance over previous clocks with foliot as a system of measuring time. I have pending perform a provisional anchorage for the pendulum but without the cycloidal cheeks, in order to compare the behavior of the clock with or without the isochronous system. When I carried all measurements I will expose the conclusions in another post. The next task is to make the case, the hands and the dial. But of course............... that will be another story. Regards. Alfonso Llamazares.