Analysis of information sources in references of the Wikipedia article "Nicéphore Niépce" in English language version.
The image of an engraving depicting a man leading a horse was made in 1825 by Nicéphore Niépce, who invented a technique known as heliogravure.
from Helmut Gernsheim's article, "The 150th Anniversary of Photography," in History of Photography, Vol. I, No. 1, January 1977: ... In 1822, Niépce coated a glass plate ... The sunlight passing through ... This first permanent example ... was destroyed ... some years later.
The image of an engraving depicting a man leading a horse was made in 1825 by Nicéphore Niépce, who invented a technique known as heliogravure.
from Helmut Gernsheim's article, "The 150th Anniversary of Photography," in History of Photography, Vol. I, No. 1, January 1977: ... In 1822, Niépce coated a glass plate ... The sunlight passing through ... This first permanent example ... was destroyed ... some years later.