Bell received his patent on March 7, 1876. Recall that he did not yet have a working device. From March 7 to 10, 1876, Bell did a series of experiments which culminated in the first transmission of speech. To show this process, we have created a kind of problem behavior graph (see Ericsson & Simon, 1984) in which the components and some of the resulting combinations are actually shown, to make it more transparent to a reader. The top of this figure is a slot diagram, based on the circuit with which Bell began this sequences of experiments. The primary purpose of the slot diagram here is to indicate the places where Bell made substitutions or changes; in this sense, the slot diagram also serves to define the problem space in which the inventor is working at a particular time (again, see Ericsson & Simon, 1984). The slot into which Bell will substitute tuning forks, reeds and other armatures is labeled 'ossicles' to indicate that his goal was to find an armature which would function like an electromechanical