A graphical computer based upon five automatic curve followers, two integrators, nine adding amplifiers, and a pen recorder was built for the transformation and combination of curves and for a simple analog computer to plot curves from equations. Heavily inked curves on 14‐in. × 17‐in. moving tables are tracked by photoelectric followers which continuously set potentiometers so that their output voltage is proportional to the curve height. The tables are positioned by voltages so that they may be made to move at a constant rate or may be individually controlled by some variable voltage. The follower output voltages may be transformed in various ways or combined algebraically with each other and used directly or indirectly through amplifiers to drive a recorder, a table, or an integrator. By this means curves may be changed in scale (linearly or nonlinearly) on either axis. Curves may be added, subtracted, multiplied, divided, or otherwise combined or operated upon in accordance with simple equations, and the result plotted in about a minute with an accuracy under favorable conditions of about ±0.02 in. Complex curves can be analyzed by fitting with algebraic combinations of simpler curves. The apparatus may be used to fit integral or differential equations to experimental data by trial adjustment of the constants. A low ac voltage increasing linearly with time represents the independent variable; the form of the equation is determined by the way in which the various units are connected and the values of constants are set by potentiometers.