(A) Mean diameter (kilometers) of minor planets discovered, 1802–2008. (B) Mean physical size (g) of mammalian species discovered, 1760–2003. (C) Mean inverse of atomic weight of chemical elements discovered, 1669–2006.
The authors are open about the obvious problem with "eurekometrics," i.e., that scientific discoveries aren't easily systematically defined. That said, that sort of difficulty is pretty common in bibliometrics and scientometrics research, and trying to come up with quantifiable proxies for relevant concepts is part of the fun (and sometimes leads to fruitful metrics, e.g., the H index). All in all, the piece is short and worthwhile and ties in with a bunch of other interesting recent bibliometrics papers (e.g., Wuchty et al.'s Science paper on teams) for those who are inclined. Check it out.