His work was on the behaviour of metals under tensile loading of short duration — a seemingly academic topic, but nevertheless of practical importance.

The day of action, which inspired teach-ins at more than 1,500 college campuses, also had practical importance.

However, a number of points arose out of that case and the previous cases which were of general practical importance in determining who was a de facto director.

That raised a point of practical importance.

There are, however, other arrangements, some with practical importance in real circuits.