This folder contains documents pertaining to the development and testing of a range and direction finder to pinpoint the locations of airplanes or cannon fire, using multiple microphones to pick up sound transmitted over land through the air. Included are reports and correspondence addressed to Edison, written by experimenter William Deans and engineer Newman Henry Holland. Beginning in October some of the work on this project was conducted at Mineola airfield on Long Island. Related documents can be found in the general correspondence folders for 1917 and in Edison Wartime Research Reports 6, 13, and 39, Charles Hummel Collection.

Approximately 70 percent of the documents have been selected. The unselected documents consist primarily of unsigned and undated rough technical notes and drawings and shop orders for parts of specific dimensions.