public Text time;
private float T;
(Time.text updates the elapsed time since the app started)

T = float.Parse (time.text);

Is it not possible?

FormatException: Input string was not in a correct format.
System.Number.ParseSingle (System.String value, System.Globalization.NumberStyles options, System.Globalization.NumberFormatInfo numfmt) (at: 0)
System.Single.Parse (System.String s, System.Globalization.NumberStyles style, System.Globalization.NumberFormatInfo info) (at: 0)
System.Single.Parse (System.String s) (at: 0)
show.Update () (at Assets/show.cs: 31)

I get an error statement.