Paintings of children trying to have fun when the grownups aren’t looking. Belgian. Franz Verhas, artist (1827-1897). Painted many portraits and genre scenes.

"The Lion." 1874.
“The Lion.” 1874. Oil on canvas. Collection of the the Museum of Fine Arts, Ghent. In the public domain in the United States it was published before January 1, 1924. via https://commons.wikimedia.org/wiki/File:Franz_Verhas_(1832-1894)_De_leeuw_(1874)_MSK_Gent_22-11-2015_11-58-03.JPG
"La lecture au salon." 1850-1894.
“La lecture au salon.” 1850-1894. Oil on canvas. In the public domain in the United States because the artist has been dead over 70 years. via https://commons.wikimedia.org/wiki/File:Frans_Verhas_-_Reading_in_the_living_room.JPG
"The Master Painter." 1877.
“The Master Painter.” 1877. Oil on canvas. Collection of the Museum of Fine Arts, Ghent. In the public domain in the United States it was published before January 1, 1924. via https://commons.wikimedia.org/wiki/File:Jan_Verhas_-_The_master_painter.jpeg
"The Broken Flower Pot." 1876.
“The Broken Flower Pot.” 1876. Lithograph. Image © 2019 – WorthPoint Corporation. Fair use license. via https://www.worthpoint.com/worthopedia/jan-frans-verhas-broken-flower-pot-537812522

Children out and about and at least trying to have fun. 19th-century genre paintings by French artist Victor Gabriel Gilbert who lived from 1847 to 1933.

"New Tricks." Undated.
“New Tricks.” Undated. In the public domain in the United States because the artist has been dead over 70 years. via https://obiskusstve.com/1684961109858061030/gilbert-viktor-gabriel/
"Grape Tasting." Undated.
“Grape Tasting.” Undated. In the public domain in the United States because the artist has been dead over 70 years. via https://pixels.com/featured/grape-tasting-victor-gabriel-gilbert.html
"Picking Wildflowers." Undated.
“Picking Wildflowers.” Undated. Image ©2018 Artnet Worldwide Corporation. Fair use license. via http://www.artnet.com/artists/victor-gabriel-gilbert/picking-wild-flowers-D3HLKRpVwyP1cLaaU0MjPA2
"Spectacle de danse." Undated.
“Spectacle de danse.” Undated. In the public domain in the United States because it was published before January 1, 1924. via https://commons.wikimedia.org/wiki/File:Victor_Gabriel_Gilbert_-_spectacle_de_danse.jpg

Victorian children having fun while looking a little overdressed. Johannes Adam Simon Oertel, artist. Living from 1823 to 1909 he was born in Germany but immigrated to the United States as a young man.

"Visiting Grandma." Undated.
“Visiting Grandma.” Undated. In the public domain in the United States because the artist has been dead over 70 years. via https://americangallery.wordpress.com/2013/02/01/johannes-adam-simon-oertel-1823-1909/
"The Colgate Family." 1866.
“The Colgate Family.” 1866. In the public domain in the United States because the artist has been dead over 70 years. via https://americangallery.wordpress.com/2013/02/01/johannes-adam-simon-oertel-1823-1909/