Combustion-engine Temperatures by the Sodium Line-reversal Method
This is a 1936 NACA technical note on measuring combustion-engine flame temperatures by the sodium line-reversal method, issued by the National Advisory Committee for Aeronautics for engine researchers. Its pictures are laboratory photographs: spectrograph exposures stacked in timed or temperature-labelled strips, and a rotated photograph of the test apparatus with tubing, gauges and burner hardware, useful to a designer wanting raw technical documentation imagery of early instrumentation.
