42 REPORT OF COMMISSION VII 
with no loss in accuracy of estimates. Further work along these same lines holds 
promise of important contributions for the future. 
The measurement of slopes on aerial photographs finds use in many phases 
of inventory work. Numerous methods have been proposed in the past for use 
by the geologist, soil surveyor, and others. Some methods are not applicable 
where photoscale cannot be accurately determined, and others are too complex. 
There is need for a simple device which will yield reasonably accurate results. 
At least one investigator is working on such a device now, which may find wide 
acceptance when perfected. 
Many other ideas relating to the use and techniques of aerial photos in 
natural resource inventories have been provided by the questionnaire respond- 
ents, and by the many publications which deal with the subject. The summary 
which is given here covers such a broad field that it cannot be expected to pro- 
vide needed details. The reader, therefore, is encouraged to search the literature 
relating to his own field of interest, to take an active part in meetings, and to 
engage in correspondence with those whose interests are the same as his. 
RESFONDENTS TO QUESTIONNAIRES* 
Wood, Waldo E. U. S. Forest Service, California 
Lommasson, Thomas U. S. Forest Service, Montana 
Bongberg, J. W. U. S. Bureau of Entomology and Plant 
Quarantine, California 
Harris, Thomas U. S. Bureau of Entomology and Plant 
Quarantine, California 
Dasmann, William Dept. of Fish and Game, California 
Ragland, W. W., Col. U. S. Army Engineers, Snow Investigations, 
California 
Merriam, L. C. National Park Service, California 
Kalmbach, E. R. Fish and Wildlife Service, Colorado 
Schultz, Vincent Game and Fish Commission, Tennessee 
Wilson, R. C. U. S. Forest Service, Oregon 
Casamajor, Paul Shasta Forests Co., California 
Waha, H. B. U. S. Forest Service, New Mexico 
Grant, Burton S. Los Angeles Dept. of Water and Power, 
California 
Ashcraft, Gordon Dept. of Fish and Game, California 
Brundall, Laurence Geophoto Services, Colorado 
Bushnell, T. M. Purdue University, Indiana 
Cosma, Duilio Corpo Forestale, Italy 
Pillewizer, Wolfgang München, Germany 
{Raindsalo, Aarne Helsinki, Finland 
{Imhof, Edouard Sederlele, Switzerland 
{Thoren, Ragnar Stockholm, Sweden 
TDrabbe, C. A. J. von Frijtag Delft, Holland 
{Baetzle, Major Etterbeek, Belgium 
LITERATURE CITED 
Andrews, G. S., 1940, “Notes on the Interpretation of Vertical Air Photographs," Forestry Chron., 
16: 202-215. 
Anon, 1951, “Log Inventory Taken from the Air,” The Timberman, 52 (5): 127, March 1951. 
* List does not include respondents to questionnaires distributed by subphase delegates. 
T Replies not yet received at time of compiling list.