As I've mentioned before, our coffee vending machine delivers a disappointing cup of coffee. It's often acrid and watery, which can only be fixed by disguising it with plenty of cream and sugar. That in itself is annoying if, like me, you prefer to drink your coffee black.

Curiously, the machine has an interesting idea of the relative sizes of the small, medium, and large coffees. On discovering that selecting "large" fills my mug just past the halfway point, I wondered if I could then top up my mug by adding a "small" to it. A fellow cubicle dweller and I performed a little ad hoc experiment to determine the ratios.

With a fresh mug under the spout, I dialled up the French roast... er... freedom roast... and selected a "large". I repeated that again with the "small" setting. As it turned out, adding the small coffee to the large made my mug overflow slightly. Logically, then, the small coffee is at about half a mug. The medium coffee, we assume, would be halfway between that and the large. The difference between the sizes must be only a few millilitres.

We will have to approach this more scientifically in the future, using a graduated cylinder to accurately measure the amount dispensed with each size. This of course, will have to wait until tomorrow, when I'm down from this extreme coffee buzz and I stop giggling uncontrollably.