Many years ago, when I was still a student, a friend of mine, Pete Moss, was using a relatively complex corkscrew to open a bottle of wine. The corkscrew broke as he used it to pull the cork from the bottle. Far from being annoyed by this, he was delighted. He explained that this was a cheap and poorly-made corkscrew, but a triumph for the engineer who designed it. He said that it was the goal of all engineers to have all the components of a machine that they design wear out simultaneously. In this case this had literally happened.
Moss was not an engineer, or even an engineering student, and neither am I. But I think that he was on to something in this remark. Certainly I think of his comments whenever I am put in that most difficult position of deciding whether to give the go-ahead for a replacement big end, or gearbox, or front suspension, or welding of sills, for a car of mine that has broken down or failed its MoT. I read somewhere that Henry Ford used to send out his engineers into local scrapyards to pick up expired Ford cars in order examine them to see if any component was not near to expiry. I have a feeling that early crankshafts tended to be 'over-engineered'.
Sadly, evolution has ensured that animal bodies, and specifically human bodies, are designed on good engineering principles. Although this is not done perfectly, it seems to me unlikely that current extrapolations of human life expectancy will prove to be correct. None of our major organs were designed to last for ever.
The more general lesson, for engineers, is that proportionate resources should be invested in the different elements of a product. The British Dreadnought battleships were designed with super-strength armour so they could withstand a hit from the biggest German guns. Unfortunately, the extra weight meant that they were sitting targets for lighter-armoured but well-armed enemy ships and were not at all the success that they Navy hoped for.
