Thirty thousand Rio school children sing under the direction of Villa-Lobos in celebration of Brazilian Independence Day [September 7th]. The band is in the right foreground.
The picture is from "South American Music Pilgrimage. V. Brazil", John W. Beattie and Louis Woodson Curtis, Music Educators Journal, Vol. 28, No. 6 (May - Jun., 1942), pp. 16-22