How do you return the Max and Min value of a series on a chart? Assume there there is only 1 series plotted across a time variable

The logical way is to calc this from the source data, however I want to o it this way as I have a number of graphs in an array where I want to set the MinimumScale and MaximumScale property based on the points in the chart. The source data is not the same for each worksheet

Regards

Joe