Template:Are You Sure/April 9

• ... that physicist and academic Thomas Johann Seebeck (9 April 1770 – 10 December 1831) discovered the thermoelectric effect, where a junction of dissimilar metals produces an electric current when exposed to a temperature gradient?

• ... that mathematician and cleric George Peacock (9 April 1791 – 8 November 1858) wrote: "Whatever algebraic forms are equivalent when the symbols are general in form, but specific in value, will be equivalent likewise when the symbols are general in value as well as in form."?

• ... that mathematician and electrical engineer Charles Proteus Steinmetz (9 April 1865 – 26 October 1923) promoted the development of alternating current, formulating mathematical theories which will advanced the expansion of the electric power industry in the United States?

• ... that Édouard-Léon Scott de Martinville (25 April 1817 – 26 April 1879) made the oldest known recording of an audible human voice, a visual recording of audio data; that de Martinville managed to sell several phonautographs to scientific laboratories for use in the investigation of sound, proving useful in the study of vowel sounds; that the phonautographs initiated further research into tools able to image sound, such as Koenig's manometric flame?

• ... that Blue Lace Hooks is a 1958 erotic thriller film starring Lana Turner and Red Buttons?