Who discovered Scientific Notation?
"Invented" is probably a better term that "discovered" when discussing the origin of Scientific Notation.
Back in the mid 1950's (1954 perhaps? I don't exactly remember) IBM produced its first "Scientific Architecture" computer, the IBM 704. Prior to this all digital computers (somebody check this. certainly all IBM computers) only could store and manipulate numbers in what was basically an integer format.
The IBM 704 contained circuits to manipulate values stored in "floating point" format. "Floating point" numbers were composed of two separate parts a "mantissa" (typically called a "coefficient" in current "scientific notation") and an "exponent".
The main market for the IBM 704 and its Scientific Architecture successors were scientists (and engineers) who needed to work with values which did not lend themselves to easy integer representation. Thus in the documentation and sales literature of the time references were to "scientific" notation (which, at the time, was viewed as a general case of the internal circuitry "floating point").
To the best of my memory, no particular engineer was credited with having designed "floating point".