INDEX 
413 
Silver Films, Dependence of Resistance of, On Method of Deposition, 
G. R. Wait 205 
Silver Films, See Hall Effect. 
Sink Hole, A Note on, E. J. Cable 181 
Smith, John E., Agricultural Geology 175 
Smith, John E., Field of Eskersi in Iowa 1^ 
Soil Water, See Forest Areas. 
Sound, Eocalization of, by Wave Phase in Open Air, Henry M. Halv- 
erson 230 
Stenography and Typing, Selection of Talent for, B. W. Robinson.... 236 
Stephens, T. C., Bird Records of Past Two Winters, 1918-1920, in Up- 
per Missouri Valley 395 
Stephens, T. C., The Taxonomic Unit, Presidential Address, 1920' 41 
Stewart, G. W., Frequency Eimit of Binaural Phase Difference and In- 
tensity Effects 218 
Stewart, G. W., Perception of Binaural Phase Difference not Caused 
by an Intensity Effect 217 
Stoner, Dayton, Bird Records of 1919-1920 in Vicinity of Iowa City. . 379 
Stroboscopic Velocity Curves, Table of Total Number of, E. E. Dodd. 219 
Stromsten, Frank A., Cladocera of the Okoboji Region 265 
Stromsten, Frank A., Copepoda of the Okoboji Region 269 
Subclavian, See Aorta. 
Surfaces, See Algebraic Surfaces. 
Sweet Corn Pericarp, Mechanical Penetration of, R. A. Rudnick and 
A. E. Bakke 129 
Swimming Pool Sanitation, Jack J. Hinman 258 
T 
Talent Survey in Music School, Esther Allen Gaw 227 
Taxonomic Unit, Presidential Address, 1920, T. C. Stephens : . 41 
Thomas, A. O., Address of, at Calvin Memorial 31 
Tone Generator, New High Frequency, C. W. He^dett 215 
Tow, Eillian, Measurement of Motility in Children 235 
Trees and Shrubs, Germination of, E. H. Pammel and C. M. King 75 
Trieschmann, Jacob E., and Knight, Nicholas, Nitrogen and other 
Compounds in Rain and Snow 159 
Typing, See Stenography. ^ 
Vacuum Tube Circuits as Source of Power for Conductivity Measure- 
ments, H. A. Geauque and F. Paul Ralston 199 
Van Wagenen, Gertrude, See Wehman and Van Wagenen. 
Vegetation, Major, of Eake Okoboji, R. B. Wylie 91 
Voice, What Constitutes, Carl I. Erickson 232 
W 
Wait, G. R., Dependence of Resistance of Silver Films on Method of 
Deposition 205 
Wait, G. R., Hall Effect and Specific Resistance of Thin Silver Films. 203 
Wallpaper, Comparative Stability of Colors in, J. M. Eindly 225 
Water, Underground, Conservation of, James H. Eees 187 
Water, See Field Water Supplies. 
