To summarize where we stand I have this list of what happened at lecture yesterday. We discussed briefly the scientific method employed by physicists. I tried to emphasize that a measurement is a comparison between two quantities of the same physical dimension. Then we went through a little problem to illustrate the importance of including units when you put numbers into physics equations. Finally by combining dimensional analysis and experiments we postulated an empirical expression for the period of a simple pendulum. What I did not get to was a discussion of how the pendulum is related to walking.