C. S. French

A CURVE ANALYZER AND GENERAL PURPOSE GRAPHICAL COMPUTER

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 construction and performance of a large grating monochromator with a high energy output for photochemical and biological investigations.

A simple monochromator with a 4×6 inch replica grating f: 3.4, which covers the range 365–1000 mμ is described. The dispersion is 3.55 mμ/mm in the second order and 7.1 mμ/mm in the first order. The slits are fixed in position and the wave‐length of the emergent beam is varied by rotating a mirror located between the telescope lens and the exit slit. It is useful for the production of monochromatic light with band widths of 10 mμ or more. With a 2×34‐mm entrance slit it produces 4×10−2 cal./min. of red light with a band width of about 28 mμ from a 350‐w tungsten lamp. The total energy output, spectral distribution and percent of stray light are given for various wave‐lengths and slit settings. The transmission of the instrument is given for the wave‐length range 365–800 mμ.