The Mechanical Analog Computers
of Hannibal Ford and William Newell
Digital Computers can only draw a straight line.
To draw a circle, a digital computer draws a lot of very short straight lines and forms them into a circle. The circle has bumps, lots of bumps.
Analog computer outputs are smooth and have no bumps or jerks, which is why the telescopes of the world are positioned by analog computers.
For details of the fire control problem, how the US Navy used analog computers from 1910 to the 1950's and how analogs were used for bomb sights, please see the following: