Feature

Design Simplification Urged to Speed Aircraft Production

Mexican Ally Found to Fight Invader

[Photograph]: Transparent Valve

Two-Purpose Machine Gun Mount Is Recent Patent

Wild Geese, Prized in U. S., Are Pests on Far South Isle

Half of Railroad Trackage Still Lacks Block Signals

Nature Ramblings: The Tale of Teeth

Indians of Both Americas Targets of “Fifth Columns”

First Glances at New Books

Front Matter

Star Study Program Will Not Be Finished Until 2019

Ancient Gateway of Kish Reconstructed in Museum