After posting just now in another forum about how our assignment of positive and negative charge goes back to Benjamin Franklin, I looked to see if his "Experiments and Observations on Electricity" (published in London in 1751) was available anywhere. About 25 years ago, I had a lot of fun reading an annotated reprint of it that I found in a library, and even quoted bits of it in some of my classes. Amazingly, it appears to be out of print in paper form. I did find the following: An online copy of the original edition, at the Rare Book Room. http://www.octavo.com/editions/frkelc/ [Broken]. http://www.gutenberg.org/etext/27610.