These data are from an undergraduate experiment
to estimate the value of the gravitational
constant, g (the acceleration of a free-falling
body at the earth's surface). For each replicate
of the experiment (row of data) a ball-bearing was
released from a pre-determined height above the 
workbench and the time taken before the ball-bearing
hit the workbench was recorded, as described in
the lecture notes.

The two columns correspond to:
   1. time taken to fall (seconds)
   2. vertical distance fallen (cm)