Chicago, Colonel A. A. Sprague, commissioner of public works; Mr. H. L. Lucas, superintendent of the Water Pipe Extension Division, and to Mr. B. W. Cullen, superintendent of the South District of the same Division; to the courtesy of the Clearing
Fig. 3.—Distribution of observations
Industrial District, through Mr. Henry H. Porter; to the kindness of the Chicago Telephone Company, and to the hearty and enthusiastic support of the University. We are especially indebted to President Burton, Mr. J. C. Dinsmore, Mr. L. R. Flook, and to Messrs. Thomas O’Donnell, Joseph Purdy, and Charles Stein.
Ryerson Physical Laboratory University of Chicago March 1925