I believe it was a Scot who invented the chronometer. Up until his time they had no idea about longitude.

The latter statement is not quite true. John gave the good oil on Harrison's invention of the chronometer but it was "only" a more accurate method of measuring time. Until then, the most accurate measurement of time, available at sea, required rather abstruse astronomical calculations; they were used to calculate longitude, about which they had very good ideas but inadequate technology.

Penicillin. Sir Alexander Fleming.

Also only partly true. Fleming's 1929 paper identified penicillin as antibiotic in vitro but he was unable to extract it. It was four years of work (from 1939 on) by Florey's team (including Chain and Heatley) that got it to the stage where it could be used.

Fleming, Florey and Chain got the Nobel, while Heatley (who invented the deep fermentation process used to produce it in bulk) got Oxford's first Honorary Doctorate in Medicine. "Without Fleming there'd be no Chain, without Chain there'd be no Florey, without Florey there'd be no Heatley and without Heatley there'd be no penicillin."

Cheers, Rowan