What did he look like?

His papers include a small group of photographs

At the wedding of this nice young couple! Three generations of Ellis Oliver Jones'
June 1949, New Haven CT.
1949 was the date also of his 50th reunion of Yale Class of 1899, for which he wrote a poem.
there os also a photograph of the attending members of that class which will appear here in due course.

Unknown location and unknown date. Presumably the place he lived in Washington DC, and quite possibly the same day as the next on, taken at our house in McLean, Virginia about 1960.

There are other pictures of him here, and here.