Curtains are traditionally made about 50% wider than the window opening, so they are thrown into folds or pleats. My friend says this is necessary to obtain optimum heat insulation. I say that the folds will just provide more surface area for air and heat to pass through. Who is right? What is the optimum configuration for a set of curtains?

Since Windows 3.0, the system has included at least one version of Patience (Solitaire). Can  anyone speculate as to:

• The number of man hours lost world wide to playing the game, as opposed to actually doing useful work.

• What could have been achieved if all the above lost time were used constructively to achieve a single goal, e.g. eradicating world hunger etc.

On looking at windows and car windscreens when it rains, I have noticed that raindrops tend to follow the previous paths of other drips when falling down the glass surface. Why is this?