This drawing is from Mariono Taccola's mid-15th Century De ingeneis. It's his idea for a sort of fish submarine contraption. The workings of the suit the submariner is supposed to wear are made clear (and I think that feather in the cap makes the whole outfit look pretty sharp), but Taccola didn't reveal the inner-workings of his fish for fear his design would be stolen. The caption that accompanies the picture in the book reads in Latin,
"I know what I am doing on the swimming fish.. I feed it oil from the sponge that he is carried by the fish who rides on it. It has inside itself what supports it, and what is self-supporting. . . . What I have acquired during a rather long time with labor shall not be known at once. Whatever I say, I say because of the ingratitude of simple people and not of the [better] men. The rest repose in my mind."He's sort of saying that, if he is funded by the "better men," he will reveal the secrets of the fabulous submarine fish.
I've become interested lately in the commodification of technical knowledge and the role books play in that process, so Taccola's weird little blueprint and his jerkiness about publishing its secrets really struck my fancy. This issue of money and knowledge and publication has reared its ugly head again in the form of The Research Works Act, which seeks to make the public pay scholarly journal fees to read the research it funded with tax dollars. Michael Eisen writes about it in an op-ed in today's (January 11, 2012) New York Times. There's a really extensive roundup of writing on The Research Works Act, which I'll be reading through and definitely writing about more over the next couple days.
If it weren't for greed we'd all be riding around on submarine fishes. Sigh.
You can read more on the subject in Pamela O. Long's "Invention, Secrecy, and Theft: Meaning and Context in the Study of Late Medieval Technical Transmission."