I had always wondered what the large concrete platforms were, and thanks to Dennis Bensheimer’s conversation with the original plant guard, Gus, I have learned this held a giant Frick steam engine with a 30 foot flywheel, which would have originally been mounted in a large pit filled with gravel and other debris nowadays.  Quoting Mr. Bensheimer from his 1987 article:

It was supposedly installed in 1896 and was one of the biggest if not the biggest refrigeration systems in the world! The engine, built by Frick, was a tandem compound cylinder type, 60 feet long with 27′ and 50′ cylinders. It ran 60 RPM and had 350 tons of cooling capacity!

Photo from 1986 courtesy of Dennis Bensheimer.

In the above photo from June 1986, which shows the same concrete mounts, we can now say for certain what this portion of the next room from the power plant was used for as Gus the guard verified this as its location.  The guard told Mr. Bensheimer that the engine was scrapped during World War II, which would make sense as the need for steel was critical then, and likewise I suspect the plant converted over to municipal power at some point before its closure.  It would have no longer needed such a giant engine to generate refrigeration.

The Sanborn maps, while extremely helpful in identifying the uses for particular rooms, is frustratingly vague in the position of large machines in each room.  Boilers are located on the map for obvious reasons; they were a giant fire hazard, and the maps were originally for insurance rates.

But what is also cool is that we can see how the second smokestack vented the boilers from the next room.  If you look closely, you can see a large steel vent connecting to the smokestack at its base.

And then back to the last room, the main room for the power plant, you can see how the rectangular vent converts to a round one before it would have attached to the boilers.

I am not sure if the broken boiler seen below was connected to the second stack, but at least one can see how the second smokestack functioned to vent smoke from the added boilers.

Update: Demolished by implosion in April 2016.