Utiliser "climb upon" dans une phrase

1. I have previously lost one son through his carelessness and I fear to send another one to a great height by means of brittle dead branches to climb upon

2. Till they climb upon the steepest chair

3. Placing three of them with their faces to the wall and arms locked, I commanded two more to mount to their shoulders, and a sixth I ordered to climb upon the shoulders of the upper two