Time to get nerdy. The ansonia movement pictured shows six wheels. This is different then what the book illustrates. First is the barrel wheel with 83 teeth. Second wheel directly above it has 60t and 8 p. It is attached to the third wheel directly above it, and the center wheel (minute wheel) to its right. Third wheel directly above the 2nd wheel has 40t and 8p. It connects to the 4th wheel. Fourth wheel (with the missing pinion on the arbor) is just right of the third wheel and has 42t and 7p. The 5th wheel or escape wheel has 35t and 6p and sits directly above the 4W. Most educational material I've come across show 5 wheels and this is what is used to determine number of vibrations per hour. This movement has six wheels, and I will discount the CW as it is not involved in driving the train. Generally the 2nd wheel drives the center (The 3rd wheel) which drives the 4th wheel. This Ansonia movement has the 2nd wheel drive the 3W and the center. So the center wheel holding the minute hand would not be part of the equation to find bph= (CWt x 3Wt x (2 x EWt)) / (3p x Ep) All multiplied by the number of turns of the CW. Since the CW is being driven by the 2W, I will use the 2W to replace the CW. That 2W rotates just under 1/2 turn for a complete revolution of the CW. Plugging those numbers in I get (60 x 40 x 42 x (2 x 35)) / (7 x 6) = 168000 / 2 = 84000 Convert to bpm = 84000/3600 = 23.3 Since this movement is different from the book, are my assumptions of substituting the 2W for the CW correct? Does this look even reasonable? My Ansonia is ticking away at about 90 oscillation per min, or 180 vibrations per minute. Thank for reading through all that! Hope you could follow along.