I just stumbled on this video someone made at the St Louis Transportation Museum.
This locomotive is the Daniel Nason , built in 1858 for the Boston & Providence railroad line. She's a wood-fired locomotive designed by George S. Griggs and built at the Roxbury shop. The eponymous Daniel Nason was the Superintendent of Transportation at the Boston depot of the Boston and Providence line. I knew from maps that the shop facility was there, mostly on the west side of the railroad tracks just north of Ruggles street, but I didn't know that they built their own locomotives there.
Boston and Providence shop, 1849 (Charles Whitney, BPL).
Note the location of the locomotive works on this 1849 map. To orient yourself, Tremont street runs across the bottom of the map, the Boston and Providence tracks come through Roxbury on the left and cross the Back bay (the water, that is) to the right. And the peninsula pointing towards the upper right is Roxbury's Gravelly Point. Parker street runs out to the point. Today, the tip of Gravelly Point would be near the intersection of Boylston street and Massachusetts avenue.
Boston & Providence shop, 1852 (Henry McIntyre, BPL).
Boston had at least two dedicated locomotive manufacturers, the Hinkley Locomotive Works, between Harrison avenue and Albany street, and the Globe works in South Boston. Both were located along the South Bay, and before Albany street was laid out on fill, both had access to piers and the harbor. The Boston and Providence, on the other hand, was land-locked, and had to bring in raw materials overland. Of course, since they owned the track, the B&P could no doubt bring it its necessities at cost.
George S. Griggs was the master mechanic at the B&P shop, and designed the locomotives built there. Griggs was hired in 1934 just as the company was getting off the ground, and built his first locomotive in 1845. At this early stage, locomotive designers had to be inventors as well as mechanics, and Griggs owned multiple patents, including a critical one for using a brick arch inside the firebox, which allowed higher burning temperatures and the use of coal.
1852, wider view (Henry McIntyre, BPL).
George Griggs lived at Milford place, shown above. It ran from Tremont st (the main street from upper right to lower left) to Grinnell st, which ran along the railroad tracks. So as was common during the 19th century, Griggs could walk (and probably see the factory) from home. He died still living there in 1870, and the company was still producing locomotives at the time based on his designs.
B & P shops, 1873 (Wards Maps).
Repair shop, 1931 (Boston Atlas).
Notice that Columbus avenue has now been laid out through Milford place, where Griggs lived, and it is now Sarsfield st. To help orient yourself, Milford place/Sarsfield street is now the short connector between Columbus avenue and Tremont street, directly opposite Melnea Cass boulevard. And the old locomotive works is now part of the campus of Northeastern University.
For a look at a very early carriage that ran on the Boston & Providence line, check out a related post on my Jamaica Plain history blog.