In a message dated 26/02/02 05:05:23 GMT Standard Time,
[log in to unmask] writes:

<< Of course, it is difficult to measure the actual dimensions. One way is to
 first measure the depth with an accurate depth gauge such as a dial
 indicator. The volume of the cell can be measured by filling it with water
 from a burette. The cross sectional area can then be found by calculation. >>

Or you can make Plaster of Paris casts from the cells and measure the plugs.
See Dave Cushman's web site for a dimensioned diagram of one of mine.

Chris