This paper describes an attachment for the Cary model 11 spectrophotometer that will print out the absorbance and wavelength at any number of preselected wavelengths, while the instrument is drawing the usual absorbance—wavelength curve Bidirectional revolut'on counters with electrical readout are used to digitize the wavelength and absorbance data; the digitized data are used to operate a parallel entry printer The program, i.e., wavelengths at which data are to be printed, is controlled by the data from the wavelength digitizer The printer will give absorbance data precise to 0.01 absorbance units when the spectrophotometer is scanning at the rate of 2 1/2 millimicrons/sec.
