A Journey Back in Time- Steam Train at Bodmin General (Movie on YouTube)
Stepping back in time the great days of the railroads. Fierce and powerful steam trains made transportation easy, fast and safe.
Photography of course was analog and mostly B&W or Sepia. The first color photo came in 1855. The first really modern color films came in 1935 when Kodak introduced Kodachrome. Developed color pictures from from those days changed color gradually. Old color images were developed and printed using a chromogenic process.
This kind of process relies on chemical reactions to produce a set of organic dyes — usually a blue, a red, and a yellow — that in combination produce the colors in your image. But these dyes, as they are the result of chemical reactions, are inherently unstable.
Another side effect is that in many cases the image develops a yellowish haze. This is because in many (but not all) color films used during the period 1936-1990, the yellow dye can increase in density over time. Perhaps the most famous example of this are Kodacolor images from 1942-1953, which had particular problems, due to some of the dye-forming agents (called "couplers") remaining in the print after processing. (For this reason, this kind of color change is often referred to as a "coupler stain.")