Looks like it's mounted to the top of the clarinet.

interesting :)

but I think it's an impossbile thing

considering that one solution could be that he's holding the tom in his hands, did you watch the second Dick Shanahan photo?

Neither the clarinet nor the saxophone is in play; was the band not playing when the picture was taken? Then Doc could easily have been setting up or tearing down his kit, holding the tom in his hands. He's even looking at the tom mount on the bass drum.

Haven't really convinced myself that's the answer though...

The clarinet is not in play, but the clarinetist's right arm with matching stage jacket is in the photo, so he's there.

ok,

any idea notice of a kind of stand coming out from the base of cymbal stand like we can suppose from the second image of Dick?

There is no visible tom mount on the bass drum. What you see is the three point strainer and snare bridge on the snare drum.

so you think he's holding on his hands to mount on the not visible stand?

In the end...not really. :)

I think I can see what appears to be the butt of a stick or brush *just* peeking out from the back of his hand, which of course suggests he was playing the drums.

I'd have to go with the tom hanging off the cymbal stand, maybe something he rigged up for the occasion, as suggested above.

I suppose the existence of a kind of hardware wich starts from base of the cymbal stand, a kind of rod, like the picuture of Dick Shanahan. nobody knows?

I saw that too. He's got his foot on the HH and his position suggests he's playing it. That is the end of a stick just past his pinky like I hold mine a lot.

I tried to hold my 13 like that, not ideal if you don't want to drop it.