Nature has her own ways of telling her secrets to man, and the commonest of those ways is what man chooses to call chance or accident. The words are convenient names and that is about all we know of the phenomena which they are used to describe.
Below are given the stories of a number of important discoveries made by accident. Perhaps it will occur to the reader that none of the discoveries was really accidental, since in each case it was the witnessing of the accident by an intelligent human being which aroused in the mind of that human being the train of thought leading to the discovery. An Australian black might watch a swaying chandelier for ten years, and he would never discover the pendulum. As a rule, special knowledge is required to make "discoveries by accident."
But the apparent working of chance in the incidents told here is obvious:
The power of lenses, as applied to the telescope, was discovered by a watchmaker's apprentice. While holding spectacle-glasses between his thumb and finger, he was startled at the suddenly enlarged appearance of a neighboring church spire.
The art of etching upon glass was discovered by a Nuremberg glass-cutter. By accident a few drops of aqua fortis fell upon his spectacles. He noticed that the glass became corroded and softened where the acid had touched it. That was hint enough. He drew figures upon glass, with varnish, applied the corroding fluid, then cut away the glass around the drawing. When the varnish was removed, the figures appeared raised upon a dark ground.
The swaying to and fro of a chandelier in the cathedral at Pisa suggested to Galileo the application of the pendulum.
The art of lithography was perfected through suggestions made by accident. A poor musician was curious to know whether music could not be etched upon stone as well as copper.
After he had prepared his slab, his mother asked him to make a memorandum of such clothes as she proposed to send away to be washed. Not having pen, ink, and paper convenient, he wrote the list on the stone with the etching preparation, intending to make a copy of it at leisure.
A few days later, when about to clean the stone, he wondered what effect nitric acid would have upon it. He applied the acid, and in a few minutes saw the writing standing out in relief. The next step necessary was simply to ink the stone and take off an impression.
The composition of which printing-rollers are made was discovered by a country printer in England. It was the established custom to ink the type on a printing-press with a pelt-ball—an ink-soaked roll of sheepskin. Having mislaid his pelt-ball, the ingenious Englishman inked the type with a piece of soft glue which had fallen out of the glue-pot. It was such an excellent substitute that, after mixing molasses with the glue to give the mass proper consistency, the old pelt-ball was entirely discarded.