That looks rather like an Anzani "Fan" type engine, there seem to be a lot of variations in the pushrod/head layouts and this is similar in appearance to that used on the 1908 Bleriot monoplane; so is this machine pre or post WWI ?
I expect it's just a trick of the light or the "ghost in the machine", but that does look like a face peering out of the dark area behind the engine ??