Equilibrium

Not your conventional see-saw or teeter-totter (as it's more commonly called in the US) I think this must be sprung for safety's sake. Not so much going Up and Down as describing a gentle arc.

       See-saw Margery Daw,

       Johnny has a new master,

       he only earns but a penny a day,

       because he can't work any faster . . .


      Up and down the city road . . . . pop goes the weasel.

       Not the best background even after trying several angles. C'est la vie.