I came across this image in the Smithsonian Institution Air & Space Museum Library. Their listing for it is simply "French Soldiers and Kite", Item No. 2002-16629. But to me it sure looks like French soldiers inspecting a Picavet suspended camera! You can click on the image for a closer look or click here for a still larger image.
I was puzzled as to exactly what was going on in the photo, since the kite seems too small. In 2003 Jan Desimpelaere from Belgium sent this note:
About "French soldiers with kite" is indeed an aerial photo system and his postillon ("messenger") but we don't see the kite. Unfortunately the kite is much higher and not visible. The man holding the suspension might be Jaques-Theodore Saconney on his early trials for the army between 1902 and 1904.
He first used Lenoir kites and worked with Emile Wenz' kites ( Eddy kites) for the Navy and later on with the typical Saconney kites but smaller than his manlifting kites.
Drachen.org has also uploaded six minute film, French Kite Aerial Photography Unit, WWI to Youtube. In the video you can see the train of larger kites that might be lifting the camera in the photo, but they seem to be using somewhat different apparatus. The larger kites appear to be Cody "war kites".