An account is given of the development of a logging system for acquiring data on punched tape from two amino-acid analysers running at different speeds. The outputs of the analysers were sampled in such a way that a visual record of the progress of each separation was retained. A method of programming the computer to edit and process the data is outlined. Results obtained from the computer showed good agreement, both within analytical systems and between systems. Manual calculations from recorder charts, made by use of the time-consuming manual method, agreed well with the computer results from punched tape and cards. Problems encountered during the period of development are discussed.