A hard-working Santa Claus is climbing a rope to the chimney. In reality it is his assistant who pulls the rope from the bottom and Santa Claus travels up without doing a hand's turn.

If we pull the string down Santa Claus' legs tighten on the rope and remain fixed, while the hands move up the rope. If we loosen the string, the hands remain fixed and the legs are pulled up by a rubber belt which goes round Santa Claus.

The principle of operation makes use of the differences in friction. The hands are tightened on the rope by means of a rubber band which presses them together. As far as legs are concerned, the string runs askew through a peg between the knees. In a bent position, the string is wrapped around the peg at an angle of almost 360°. The principle of wrapping the ship rope round the mooring peg used by seamen explains why friction force of the string round the legs is greater than the friction force of the hands. The legs remain motionless on the string while the hands move upwards.

To climb up the rope, Santa Claus utilises the change in friction force in 'bent down' and 'straighten up' position of his body.

Pulling the string down brings about straightening up of the Santa's body - the angle at which the string is coiled around the peg gets sharper, the friction at the legs gets reduced, but still it is static and it is greater compared to the dynamic friction affecting the movement of the hands.

When at last Santa straightens his body up, the friction at the legs gets is lesser than (now static) friction at the hands: the legs move upwards.

Of course, the grip of the hands on the string should not be too strong, so that they still can slide along the string when the legs are motionless and not too loose, so that they can remain motionless, when Santa bends down after pulling himself up.