An electrical frequency analyzer

H. Fletcher: I desire to emphasize the tremendous difference in the time required for obtaining analyses by means of this machine and by the method which has usually been employed in the past. After the electrical connections are made, all you have to do is to press a button and then after waiting five minutes you have a photographic record of the analysis before you are ready for examination. This machine will do in two or three hours what previously required as much as two or three months´ work for obtaining the spectrum analyses of such sounds as the output of a horn or organ pipe.