What was the wonderful work of Mark Scalliot? Probably the smallest lock and key ever made. He was a London blacksmith, and this piece of mechanism (1578) was of iron, steel, and brass, all of which, with a pipe-key to it, weighed but one grain of gold. He also made a chain of gold, consisting of forty-three links, and having fastened the chain to the lock and key, he put the chain around the neck of a flea. The flea could hop around with ease in spite of the weight. The lock, key, chain and animal, all in a lump, weighed only one grain and a half.

— Albert Plympton Southwick, Handy Helps, No. 1, 1886