Infinite-axis telescope

The first Newtonian telescope was mounted in this way; the ball was held in place by wrought iron springs.

[1] There are modern commercial and amateur mount designs for Newtonian telescopes that have the "ball" built into the base of the optical tube assembly.

These mounts have the advantage of being mechanically simple and allow the observer to rotate the eyepiece to any side of the telescope for easier viewing.

Some types have even been adapted for equatorial tracking by motorizing one of the bearing surfaces to turn the ball at the rate of one revolution per day.

An advantage of infinite-axis telescopes is that there is no "dead-zone" where one axis must move infinitely fast in order to track the stars, as is the case with alt-azimuth mounts.