That first image is a 37mm "Tube SACA Mle 18, STAN". It was a conversion of the standard "tube cannon" M1902. According to A Gun For All Nations, Volume II by Robert Mellichamp, it was meant to be an anti-aircraft gun rather than anti-tank.
I wonder if Flying Guns of World War 1 by Anthony Williams wouldn't have something on that second gun you have pictured?
Anyway, hope that helps!
Matt
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“[B]ut these tanks are machines, their caterpillars run on as endless as the war, they are annihilation, they roll without feeling into the craters, and climb up again without stopping..." -Erich Maria Remarque