When I was ten my family returned to live in Philadelphia. Soon I met a boy named T. Martin Flatley, who was in the same grade in school as I, and who had a passionate interest in the locomotives of the Pennsylvania Railroad. A third young railfan was Bill Barnes, but Bill was somewhat separated from Martin and I because his main interest was in the engines of the Reading Company. For some reason none of us was very much interested in the Baltimore & Ohio, the other railroad that ran through Philadelphia. Martin and I were welcomed by railroad men in every engine yard and roundhouse in the area and thrown out of most of them by railroad detectives.
We "collected" engine numbers. This was slightly less trivial than it sounds because the Pennsy, as the railroad was nicknamed, before 1920 had the unusual practice of giving a new locomotive the number of one that had just been scrapped. Thus number 1 was a small Consolidation (2-8-0) type, class H6sb, while number 8 was a large Pacific (4-6-2), class K4s, and number 16 was a large Atlantic (4-4-2), class E6s. All the numbers in between were taken by other engines of other types; I only happen to remember these three. Each of us, in the common practice of pre-teens, had a "favorite" engine. Mine was number 6872, a class M1 Mountain (4-8-2) type. I haven't a picture of it, but here is a mate, number 6940.
PRR No. 6940, Class M1, Mountain(4-8-2) type built Baldwin Locomotive Works, 1926.
The engine in the right background is a Consolidation, probably class H6a, built around the turn of the last century, 26 or 27 years before I took the picture.