CONTENTS 
Anthropology. — Peabody Museum Arizona Exploration, 1920 
By A. V. Kidder and S/J. Guernsey 69 
Physics. — The Open Mercury Manometer Read by Displacement Inter- 
ferometry ... ' . . By C. Bar us 71 
Chemistry. — Studies on Catalysis. I. The Reduction of Uracil to Hy- 
drouracil By T. B. Johnson and E. B Brown 75 
Chemistry. — The Application op a Differential Thermometer in Ebulli- 
oscopy By A. W. C. Menzies and S. L. Wright 77 
Chemistry. — A Differential Thermometer . . By A. W. C. Menzies 81 
Mathematics. — Normalized Geometric Systems . . . By A. A. Bennett 84 
Mathematics. — Problems of Potential Theory . . By G. C. Evans 89 
Physics. — Thermo-Electric Action and Thermal Conduction in Metals: 
A Summary By E. H. Hall 98 
