CRANV1P1 Formation of Index Languages chapter Cyril Cleverdon Jack Mills Michael Keen Cranfield An investigation supported by a grant to Aslib by the National Science Foundation. Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. - 63 - abe abf abfa abfb abfc abfd abfda abfe abfea abfeb abff abffa abffb [OCRerr]xperimental wind tunnel methods] [Visualisation methods] Using shadowgraph (3) Using photography. Photorecording (3) Drum camera (1) Photomultiplier (1) Television (1) Motion picture (2) High speed (1) Schlieren (2) Spa rk (1) Photomultiplier (1) Interferometry (2) Fringe shift (1) Interferential strioscopy (1) etc. The full hierarchy provides twenty-nine classes. The first reduction, replacing the terms marked (1) by a see reference to their immediate containing head (e. g. Drum camera see Photography), leaves eleven classes, namely a Experimental wind tunnel methods ab Visualisation methods aba Using smoke,vapours etc. abb Using coatings, flows etc. abc Using spectrum abd Using stroboscope abeUsing shadowgraph abf Using photography abfd Motion picturą abfeSchlieren abff Interferometry The second reduction, similarly replacing terms marked (2), which now include those originally marked (1), by see references to their containing heads, leaves eight classes, namely a ab aba abb abc abd abe abf Experimental wind tunnel methods Visualisation methods Using smoke,vapours etc. Using coatings, flows etc, Using spectrum Using stroboscope Using shadowgraph Using photography The third reduction similarly replacing terms marked (3), leaves two classes, namely a Experimental wind tunnel methods ab Visualisation methods In this way figures are obtainable to show the exact effect of moving, say, from