This wheel makes the left end of the lever heavier than the right, and in sinking it drives the clock for one minute, but at the sixtieth second it "remounts" by the action of the clock weight; hence the name, "remontoir." Note here that the big weight does not directly drive the clock; it only rewinds it every minute. The minutes are shown on the dial to the right and its hand jumps forward one minute at each sixtieth second as the lever remounts; so if you wish to set your watch to this clock the proper way is to set it to the even minute "on the jump." The hour hand is on the dial to the left. By this remounting, or rewinding, the clock receives the same amount of driving force each minute. The complete clock is shown in Fig. 31, the large weight which does the rewinding each minute being plainly visible. The pendulum is compensated with steel and aluminum, so that the rate of the clock may not be influenced by hot and cold weather. Was built in 1901 and is the only one I can find room for here. It is fully described in "Machinery," New York, for Nov., 1901. I have built a considerable number, all for experimental purposes, several of them much more complicated than this one, but all differing from clocks for commercial purposes. Pallets like O O in Fig. 29 are often made of jewels; in one clock I used agates and in another, running thirteen months with one winding, I used pallets jeweled with diamonds. This is done to avoid friction and wear. Those interested in the improvement of clocks are constantly striving after light action and small driving weights. Conversely, the inferior clock has a heavy weight and ticks loud. The "gravity escapement" and others giving a "free" pendulum action would require too much space here, so we must be satisfied with the few successful ones shown out of hundreds of inventions, dozens of them patented. The pendulum stands at the top as a time measurer and was known to the ancients for measuring short periods of time just as musicians now use the metronome to get regular beats. Galileo is credited with noticing its regular beats, but did not apply it to clocks, although his son made a partially successful attempt. The first mathematical investigation of the pendulum was made by Huyghens about 1670, and he is generally credited with applying it to clocks, so there is a "Huyghens" clock with a pendulum instead of the foliot of De Vick's. Mathematically, the longer and heavier the pendulum the better is the time-keeping, but nature does not permit us to carry anything to the extreme; so the difficulty of finding a tower high enough and steady enough, the cumbersomeness of weight, the elasticity of the rod, and many other difficulties render very long and heavy pendulums impracticable beyond about 13 ft. which beats once in two seconds. "Big Ben" of Westminster, London, has one of this length weighing 700 lb. and measuring, over all, 15 ft.