Coming back to the map "Attempts at Flight 1890 - 1909" (see:
http://www.pprune.org/aviation-history-nostalgia/540496-wright-brothers-just-glided-1903-they-flew-1908-a-19.html#post8518036 ) I have come to the conclusion it is a total mess.
For instance, the Sep. 12, 1906 flight of Jacob Ellehammer does not appear on the diagram. There is also a green point situated around 1901 and corresponding to a more that 403 feet flight done by the Wright brothers which can not be a powered flight. The chart is a mixture of selected powered flights and glides that does not make too much sense.