Airplane Propeller Manufacture
Problems Which Have Been or Need to be Studied
Features
How a Season Differs from Year to Year
The Rational Causes of Variations in Our Summers and Winters
Notes on Drop Valves for Steam Engines
Results of Experience With Slow-Speed Land Engines, Perhaps Useful Also in Designing Other Types
Ants of High and of Low Ability
A Study in the Psycho-biology of Various Ants
Printing Silks
Old Hand-Block Printing Contrasted With Present Expensive Power Machines
Recent Progress in Aerial Photography—II
Remarkable Improvements During War and Applications to Peace-Time Needs
Light and Organisms
Orienting Effects of Monochromatic Light on Fucus Spores and Rhyzoids
Gathering Chicle Gum for American Gum Chewers
Collecting, Preparing and Shipping Chicle Gum for the United States
Copying Fingerprints—I
New Methods for “Lifting” or Transferring Fingerprints on Objects by Prepared Paper or Foils