Just for accuracy's sake, that 0-6-0 is Ma and Pa No. 30 on the Baltimore turntable.  The roundhouse still stands, but in poor repair.  It was taken over by the city's highway department as a maintenance depot but maintenance apparently doesn't extend to the building.  The Baltimore Streetcar Museum track runs alongside Falls Road in front of the building.  The turntable pit was filled in long ago.  Take a look with Google streetview.

I don't have a ready reference handy, but I once came across an article that included the description of the turntable.  It used brake air, which was hooked up to a cylinder under the table.  The cylinder operated a form of ram mounted on an angle.  The ram pushed against the tie stubs that supported the ring rail, one at a time.  A guesstimate of 49 tie stubs for half of a 65 foot turntable and 5 seconds per pulse comes to about 4 minutes to turn a loco. 

There doesn't seem to be a date on the diagram, but I'm assuming it is from the late 1800's.  I agree that this type of installation would only be really practical in a heavy-use situation.  It is likely that by 1900 most terminal turntables had been electrified.  Some lighter-duty units used compressed air from the loco's brake system and, as noted, some were "Armstrong" - several men shoving on poles extending from the end of the turntable. 

Well, the good news is the re-issue of the Decapod.  The bad news is the MSRP of $549.00.  Wonder if the tariff war has anything to do with the price jump?

Oh, wow! Sad news indeed.  Hope the business continues.

You may have to do what I did and order the complete trucks with metal gears installed.  They were about $33 per truck.

They do have a very impressive collection of steam locos there.  Visited few years ago during the Cleveland NMRA convention.  At one time they had about four operable steam locos.  The owner, Jerry Jacobson, also owned the Ohio Central RR, whose main line runs past the roundhouse.  He sold out (to NS?) and passed away not too long ago.  When I was there, CP 1293 was operable and they were restoring an ex-LS&I heavy 2-8-0.  Their GT 4-8-4 was operable, but may have run out of FRA time by now.  And yes, Jerry did collect some vintage diesels too.

Always check the gauge of the wheelsets with an NMRA gauge.  If the gauge is slightly wide, this will cause derailments.  Also check the track gauge of the turnout, and giving a few swipes to the point rail with a small file is also a good thing.

The photo would have been taken after 1893 when the 3rd Ave. trolley line went to cable operation.  You can see the slot between the running rails.  In 1909 the system went to electric operation.  The below-ground cableway was rebuilt to a conduit system, like Washington DC used into the early 1960's.  I tend to agree with Trainman that the photo is around 1900 or earlier.  Old elevated Forneys went to a lot of places - cane plantations, logging railroads, would-be trolley lines that didn't have the resources to install the electrics, etc. 

Re:  855, the Best Friend was notable as the first all U.S.-built steam loco in service.  It was also the first U.S. steam loco to suffer a boiler explosion six months after it went into service.  Reputedly, the fireman got annoyed with the constant noise of the safety valve and shut it off.  He did not survive the explosion.  The modern replica was built in 1928 to commemorate the centenary of the company. 

No. 857 shows the working guts of the Pennsylvania RR's DD-1.  The locos were a paired set of 4-4-0's and used with the opening of the electrified portion between Manhattan Transfer, NJ and Penn Station.  IIRC, there is a representative in the museum in Strasburg. 

Just when you think there are things you will never see run again, we get No. 18 in Colorado, the Big Boy on the UP, and the C&O 1309 coming in Cumberland. 

Well, whoever posted the description of those FA's doesn't know anything about trains.  First, they are HO, not On30.  Second, they aren't Bachmann since Bachmann has never, to my knowledge, made any FA locos.  I'm going guess they might be Model Power undecs. 

Great work, Sid.  I real nice visual how-to on assembling a craftsman kit. 

Picture didn't come throught for me.

Yeah, there aren't many places you can move a 3-foot gauge oil-fired Shay and run it.  IIRC, this loco had once been used at the Georgetown Loop RR.  If so, it has operated in relatively recent memory.  You can probably expect to spend several hundred thousand dollars to get it running, because it will certainly need a full FRA rebuild.  Nice to dream, though.