Since you refer to my book review in the Related Posts, I feel I am obligated to say Lord Kelvin and leave it to the readers to look at the review and see why I say that.
While you could argue that any of the men that Keithley honors is a genius, he bestows that honor on only one: James Clerk Maxwell. While we all know about his famous equations,
Dave van Ess of Cypress Semiconductor (http://www.cypress.com/?id=2201&month=3&year=2111 ) is fond of noting that the form of Maxwell's equations that we know and love (!!!!) was in fact developed from Maxwell's original formulae by Oliver Heaviside. Irrespective of who was responsible, if my career was to have been built on the understanding of any form of Maxwell's equations, I would have been selling shoes.
Who of the famous scientists, whether or not covered in Keithley's book, do you credit most for the job you have today?
In fact I credit some not so famous scientist and engineers- those many engineers who write app. notes especially the early Intel App Notes and the National Semiconductor Linear Application Notes.
Earlier when these hardware innovation were done, the scientist name got associated with those inventions but these days engineers who invent or write the app are hardly given individual credit. Its just the company's name.
In my book, anyone who can intuit something previously unknown, and then go about the difficult task of proving it with instruments of their own making, qualifies as some sort of genius.
But I agree that Maxwell did show that extra bit of insight, that tied together Gauss' Laws, Faraday's Law, and Ampere's Law, in one beautifully symmetric package. I laughed when our sophomore year physics book said that the symmetry of Maxwell's equations was "good for the soul." Honest, its very words. But there's something to that.
We all take these for granted now. Even, for instance, that recent discussion of transmission lines. These concepts are pervasive in everything we do.
Before Oliver Heaviside, electricity was the province of scientists and inventors. After Heaviside, there was electrical engineering. He changed Maxwell's equations from twenty to the four we know, created the engineering mathmatics we spend semesters in college learning and defined the transmission line equations used in power distribution and printed circuit boards.
Heaviside's masterworks are free online at the internet archive. It's amazing how much he predicts the theory of relativity and yet could not accept it and said it must be some kind of joke. In that way, Einstein ended his career, because the scientific world he was mastering was suddenly gone.