The first known traffic signal appeared in London in 1868 near the Houses of Parliament. Designed by JP Knight, it featured two semaphore arms and two gas lamps. The earliest electric traffic lights include Lester Wire's two-color version set up in Salt Lake City circa 1912, James Hoge's system (US patent #1,251,666) installed in Cleveland by the American Traffic Signal Company in 1914, and William Potts' 4-way red-yellow-green lights introduced in Detroit beginning in 1920. New York City traffic towers began flashing three-color signals also in 1920.

Garrett Morgan's cross-shaped, crank-operated semaphore was not among the first half-hundred patented traffic signals, nor was it "automatic" as is sometimes claimed, nor did it play any part in the evolution of the modern traffic light. 

The possibility of using blood plasma for transfusion purposes was known at least since 1918, when English physician Gordon R. Ward suggested it in a medical journal. In the mid-1930s, John Elliott advanced the idea, emphasizing plasma's advantages in shelf life and donor-recipient compatibility, and in 1939 he and two colleagues reported having used stored plasma in 191 transfusions. (See historical notes on plasma use.) Charles Drew was not responsible for any breakthrough scientific or medical discovery; his main career achievement lay in supervising or co-supervising major programs for the collection and shipment of blood and plasma.

Dr. Williams repaired a wound not in the heart muscle itself, but in the sac surrounding it, the pericardium. This operation was not the first of its type: Henry Dalton of St. Louis performed a nearly identical operation two years earlier, with the patient fully recovering. Decades before that, the Spaniard Francisco Romerocarried out the first successful pericardial surgery of any type, incising the pericardium to drain fluid compressing the heart.

Surgery on the actual human heart muscle, and not just the pericardium, was first successfully accomplished by Ludwig Rehn of Germany when he repaired a wounded right ventricle in 1896. More than 50 years later came surgery on the open heart, pioneered by John Lewis, C. Walton Lillehei (often called the "father of open heart surgery") and John Gibbon (who invented the heart-lung machine).

The list goes on and on and on