'There is of course the question of public safety,' said Vetinari. 'Did I hear you say earlier you have blown up... "one or three" I think was the phrase?"

'I made those explode a-purpose, to see exactly how it 'appened. That's the way to get knowledge, you see, sir.'

Raising Steam, Terry Pratchett

Regarding the first steam engine in Pratchett's fictional world.