To address a couple of questions:
Re: "At the risk of getting off-topic, what's the best book to learn about the Delta Lines and Frank Ellison's philosophies on layout design and operation?"
Available with a digital subscription to OGR are O Scale Railroading Run 108 from December 1989 and O Gauge Railroading Run 109 from February 1990 (that's when the change from OSR to OGR occurred) that are special issues highlighting Frank Ellison and the Delta Lines. Particularly noteworthy is an article by Frank Ellison from Model Builder magazine titled "A Journey on Delta Lines" intertwined with an article by Elliott Kahn, a Delta Lines member, titled "Memories of Delta Lines."
Frank Ellison's signature work, "The Art of Model Railroading," a six-part series in Model Railroader magazine from 1944 is available here: https://www.trains.com/wp-cont...ine_extras_new_1.pdf
I suspect the most cost effective way to read Frank Ellison's other writings now is to join (pay for) the trains.com website from which Model Railroader magazines can be downloaded. Here's the list I have compiled of Model Railroader issues that have articles by Frank Ellison (there are a couple of post-1970 reprints/condensed versions not listed):
1941 - Aug, Nov; 1942 - Oct; 1943 - Jan, Jun, Sep, Oct, Dec;
1944 - "The Art of Model Railroading": Mar through Aug; 1944 - Sep, Oct, Nov, Dec; 1945 - Jan, Feb, Mar, Apr, May, Jun, Dec;
1946 - Apr, Aug; 1947 - Mar, Apr; 1949 - Aug, Nov, Dec; 1950 - Jan, Feb, Mar, May, Jun, Jul, Aug, Oct, Nov, Dec;
1951 - Jan, Feb, Mar, May, Jun, Sep, Nov, Dec; 1955 - Nov, Dec; 1956 - Jan;
1964 - "The Art of Model Railroading" reprint: Aug through 1965 Jan.
If I had to pick only one issue, I would go with the November 1955 issue which is a concise but comprehensive review of the Delta Lines focusing on a typical operating night. FWIW, I feel "The Art of Model Railroading" was presented better in the 1964-1965 reprint than in the original 1944 series.
Re: Color photographs of the Delta Lines. The only known color photographs of the Delta Lines are those that Bill Harry took in 1955 using the flood lights that a local televison station had set up to make a video news story on the Delta Lines, (Unfortunately, the video seems to have been lost or destroyed.) While we are fortunate to have any color photographs, they do not show Delta Lines at its best as they were taken after the death of Frank's wife Nellie in early 1954. Her illness in late 1953 marked the end of the regular weekly operating sessions. The pictures show that some disassembly of the railroad and removal of some scenic items had occurred. But still, what's not there is very minor; the pictures are excellent reference material and provide an unparalleled historical record of what the Delta Lines looked like.
