it was the head of the hammer which was responsible for such exceptional sounds, he examined all the hammers and found that the weight of each individual hammer was in a particular proportion to that of another: 12, 9, 8 and 6 pounds. You could hear an octave each time the largest and the smallest hammer struck the anvil (12 : 6), a pure fifth emerged in the relationship between the 12- and 8-pound hammers; he found the straight fourth in the relationship between 8 and 6 or 12 and 9, and the whole note rang out when the two middle hammers were being used (9 : 8).' This means that the reason why these sounds were in harmony was attributable to the mathematical relationship that existed between them.