by NASA Deputy Administrator Gregory on December 17, 2003 at Kitty Hawk
In 1895, as president of the Royal Society, Kelvin is quoted as saying, "Heavier-than-air flying machines are impossible," proven false a mere eight years later with the flight of Orville and Wilbur Wright's Wright Flyer at Kitty Hawk in 1903. In 1897, he predicted that "Radio has no future;"  while the popularity of radio did not appear in his lifetime (it was not until the 1920s and 30s that it attained any degree of popularity), the statement was nevertheless proven false.
Wikipedia also discusses work of Kelvin relevant to Edison, the light bulb, and dc current:
In 1893, Thomson headed an international commission to decide on the design of the Niagara Falls power station. Despite his previous belief in the superiority of direct current electric power transmission, he was convinced by Nikola Tesla's demonstration of three-phase alternating current power transmission at the Chicago World's Fair of that year and agreed to use Tesla's system. In 1896, Thomson said "Tesla has contributed more to electrical science than any man up to his time."
Recall that, at the Chicago Fair in 1893 (Columbian Exposition), the light bulbs of Edison were NOT used, even though the Edison patent was in effect until 1894. All the talk about the Edison patent "blocking innovation" is NOT in accord with what was actually happening at the time.
They really ought to have known better. including
"Our future discoveries must be looked for in the sixth decimal place."
-- A. A. Michelson, 1894
[On the occasion of the dedication of a physics laboratory in Chicago,
noting that all the more important physical laws had been discovered]
"X-rays will prove to be a hoax."
-- Lord Kelvin, president, Royal Society, 1895
"Flight by machines heavier than air is impractical and insignificant, if
not utterly impossible."
-- Simon Newcomb, Director, U.S. Naval Observatory, 1902