10: Frederick W. Shurlock, Derby, England. 18: L. L. Whyte, Cambridge, England. 24: Prof. Moritz Schlick, University of Rostock, Germany. 30: C. E. Rose, M.E., Little Rock, Ark. 33: H. Gartelmann, Bremen, Germany. 35: Prof. Joseph S. Ames, Johns Hopkins University, Baltimore. 47: James O. G. Gibbons, East Orange. N. J. 82: Charles H. Burr, Philadelphia. 101: L. F. H. de Miffonis. B.A., C.E., Ottawa, Canada. 102: Charles A. Brunn, Kansas City. 106: J. Elias Fries, Fellow A.I.E.E., Birmingham, Ala. 114: Dean W. P. Graham, Syracuse University, Syracuse, N. Y. 115: Rev. George Thomas Manley, London. 116: Prof. J. A. Schouten, Delft, Netherlands. 121: Elwyn F. Burrill, Berkeley, Cal. 125: Dorothy Burr, Bryn Mawr, Pa. 130: C. W. Kanolt, Bureau of Standards, Washington. 135: Robert Stevenson, New York. 139: Leopold Schorsch, New York. 141: Dr. M. C. Mott-Smith, Los Angeles, Calif. 147: Edward A. Clarke, Columbus, O. 149: Edward A. Partridge, Philadelphia. 150: Col. John Millis, U. S. A., Chicago. 152: George F. Marsteller, Detroit. 156: D. B. Hall, Cincinnati. 165: Francis Farquhar, York, Pa. 178: Dr. George de Bothezat, Dayton, O. 179: Professor A. E. Caswell, University of Oregon, Eugene, Ore. 182: C. E. Dimick, New London, Conn. 186: Earl R. Evans, Washington, D. C. 188: Norman E. Gilbert, Dartmouth College, Hanover, N. H. 192: A. d'Abro. New York. 194: L. M. Alexander, Cincinnati. 197: Kenneth W. Reed, East Cleveland, O. 198: Prof. E. N. da C. Andrade, Ordnance College, Woolwich, England. 216: Professor Andrew H. Patterson, University of North Carolina, Chapel Hill, N. C. 220: Prof. Arthur Gordon Webster, Clark College, Worcester, Mass. 221: Walter van B. Roberts, Princeton University, N. J. 223: Paul M. Batchelder, Austin, Tex. 227: Prof. R. W. Wood, Johns Hopkins University, Baltimore. 229: E. P. Fairbairn, M.C., B.Sc., Glasgow. 231: R. F. Deimel, Hoboken, N. J. 232: Lieut. W. Mark Angus, U. S. N., Philadelphia. 235: Edward Adams Richardson, Kansas City. 263: Prof. William Benjamin Smith, Tulane University, New Orleans. 264: James Rice, University of London, London. 267: William Hemmenway Pratt, Lynn, Mass. 272: R. Bruce Lindsay, New Bedford, Mass. 283: Frank E. Law, Montclair, N. J. In addition to the specific credit given by these references for specifically quoted passages, the Editor feels that he ought to acknowledge his general indebtedness to the competing essayists, collectively, for the many ideas which he has taken away from their text to clothe in his own words. This does not mean that the Editor has undertaken generally to improve upon the language of the competitors, but merely that the reading of all their essays has given him many ideas of such complex origin that he could not assign credit if he would. TABLE OF CONTENTS