DISCOVERY OF ELECTRON WAVES 393 Equation ot lineλ= m.2my2=始 (m2)(= 1225 Fig 4. Test of the de Broglie formula i=kp=/o. Wavelength computed from diffraction data plotted against yv, (v, primary-beam voltage). For precise verifica- tion of the formula all points should fall on the line 1,= 12. 25/V"plotted in the dia- gram( x From observations with diffraction apparatus; o same, particularly reliable: D same, grazing beams. o From observations with reflection apparatus. to whose skill and perseverance a great part of the success of the definitive experiments is due, succeeded Dr. Kunsman in 1924 I would like also at this time to express my admiration of the late Dr H. D. Arnold, then Director of Research in the Bell Telephone Laboratories, and of Dr. W. Wilson, my immediate superior, who were sufficiently far sighted to see in these researches a contribution to the science of communica- tion. Their vision was in fact accurate, for today in our, as in other industrial laboratories, electron diffraction is applied with great power and efficacy for discerning the structures of materials But neither of this nor of the many beautiful and important researches which have been made in electron diffraction in laboratories in all parts of the world since 1927 will I speak today. I will take time only to express my admiration of the beautiful experiments-differing from ours in every re- spect- by which Thomson in far-away Aberdeen also demonstrated elec-DISCOVERY OF ELECTRON WAVE S 393 Fig. 4. Test of the de Broglie formula l = k/p = h/mv. Wavelength computed from diffraction data plotted against I/V½ , ( V, primary-beam voltage). For precise verifica￾tion of the formula all points should fall on the line l, = 12.25/V ½ plotted in the dia￾gram. ( x From observations with diffraction apparatus; o same, particularly reliable; › same, grazing beams. o From observations with reflection apparatus.) to whose skill and perseverance a great part of the success of the definitive experiments is due, succeeded Dr. Kunsman in 1924. I would like also at this time to express my admiration of the late Dr. H. D. Arnold, then Director of Research in the Bell Telephone Laboratories, and of Dr. W. Wilson, my immediate superior, who were sufficiently far￾sighted to see in these researches a contribution to the science of communica￾tion. Their vision was in fact accurate, for today in our, as in other industrial laboratories, electron diffraction is applied with great power and efficacy for discerning the structures of materials. But neither of this nor of the many beautiful and important researches which have been made in electron diffraction in laboratories in all parts of the world since 1927 will I speak today. I will take time only to express my admiration of the beautiful experiments - differing from ours in every re￾spect - by which Thomson in far-away Aberdeen also demonstrated elec-