Have you ever thought about why wishing wells? There's a very good scientific reason for them.In the past before running water and purification plants people had to rely on wells. So they'd dig a well. Then for good luck they'd toss a silver coin into the well. Why? Silver just happens to have disinfecting properties. Which is why rich people often used silver ware for their food,it kept their food fresher for longer. So if you threw a silver coin into someones well then you were wishing them good luck with their water supply by helping the water stay pure. It carried on so people threw any old coin in and the real reason was lost.
As an interesting point, and why I am teling you this, one of the washing machine manufacturers has brought out a washing machine that features a silver anode that releases silver particles into the wash, thus keeping the machine bacteria free and your clothes cleaner. So now you know.