Sci-fi novelist and Star Trek uber fan Robert J. Sawyer got me thinking recently about the Engineering section on the original NCC-1701 and its sister ships. On his Facebook page, Rob made an excellent point: 

Ever wonder what that forced-perspective thing behind the grill in Engineering is supposed to represent?

There’s really no doubt; it’s canonically answered in THE DOOMSDAY MACHINE. Scanning the one in the identical Engineering Room aboard the ENTERPRISE’s sister ship, the U.S.S. CONSTELLATION, Scotty refers to it as one of the impulse engines.

The relevant dialog:

KIRK [in the Constellation’s Auxiliary Control room]: “Scotty, where’s that power?”

SCOTT [crouching in front of the forced-perspective set component and scanning it with his trident scanner]: “Coming, sir. If I push these impulse engines too hard in the condition they’re in, they’ll blow apart.”

I can’t argue with Scotty. The dialogue is right there. But I always figured that section of Engineering was the warp core, a horizontal version of the vertical design we see on the Enterprise D and the Voyager. The core in Star Trek: The Motion Picture seems to be a hybrid or transitional design.

And that belief was supported by Enterprise, which suggested horizontal warp cores were an early design, later replaced with vertical alignments.

Also, the lit conduits visible in this later scene from The Doomsday Machine look like the ring-shaped pipes on the D’s warp core.

It is possible, of course, to explain away the dialogue in The Doomsday Machine. Perhaps Scotty was scanning the warp core when Kirk called down and his comment about the impulse engines was unrelated to his specific location at that time. Or (likely the real reason) director Marc Daniels thought the shot would look good against that section of the set, and didn’t wonder if the placement made sense. 

But the thing about adhering to what is seen on screen is you have to adhere to it.

And the location fits

The proposition that the equipment seen in The Doomsday Machine is not the warp core is supported by the relative locations of Engineering and the impulse engines. While the placement of neither is specified on screen, The Making of Star Trek (which I consider to be just slightly less authoritative than the screened episodes) has this to say on page 171:

The primary hull is 417 feet in diameter and is 11 decks thick through the middle. Designed to operate separately from the rest of the ship, the saucer therefore contains all elements necessary for independent operation.

Propulsion for the primary hull is provided by impulse power. The impulse engine section is located at the bottom rear end of the saucer. Headquarters for the engineering division is also located in the same area, as are main engineering control facilities plus sufficient repair, storage, and other facilities to service the primary section when detached from the stardrive sections of the vessel.

That seems definitive: main Engineering is adjacent to the impulse engines. Also, fans who grew up in the 1970s saw this proximity in the Star Trek Blueprints by Franz Joseph and on the diagram printed on the AMT Enterprise box.

Those sources are not canon but they agree with The Making of Star Trek.

Which means Scotty worked in the saucer section

When I first started watching TOS, I figured engineering was in the secondary hull because the warp engines attach to it. But a few years later I studied the Making of and the blueprints as if I had to sit an exam on them, so I learned better.

But I never connected that scene in The Doomsday Machine to the impulse engines. Thanks, Rob.

But wait a minute

A friend in Trek, Subcommander Tal on Twitter, also made a good point, in response to this piece: at the end of Day of the Dove, the entity flees Engineering and exits into space at the forward end of the secondary hull. That shows Engineering is in the secondary hull.

The red circle is where the entity exits the ship. The yellow circle is the entity itself.

But, again, there is evidence on the other side. In the same episode, just after Mara leaves Engineering to sabotage the main life-support couplings, we see her walking down a curved corridor — which means Engineering is in the saucer section.

And I recently watched The Paradise Syndrome for the first time in a while (and I was surprised how little I liked the episode). Scotty looks towards the maybe warp core and reports to the bridge: “I can’t give you warp nine much longer, Mister Spock. These engines are beginning to show signs of stress.”

So the canon sources do not agree, and I think that means TOS fans can justifiably hold to either location for Engineering and can also choose whether that pulsating bank of equipment is the warp core or the impulse engines. My rule has always been that what we see on screen is the final word and that collectibles like the Star Trek Blueprints, the novels, and the model kits — beloved though they may be — are not reliable sources. However, I have always made an exception for The Making of Star Trek; as I said above, I consider it only a half step down from on-screen proof.

So now I don’t know where Engineering is. Locating it in the secondary hull still makes sense to me, but I also know that almost all the people who made TOS great were gone by the third season and that, in contrast, The Making of Star Trek was written at a time when the creative people were not only present but still had the energy to really care about the show. That book clearly states Engineering is in the primary hull and gives a good reason why those control systems are there: “Designed to operate separately from the rest of the ship, the saucer therefore contains all elements necessary for independent operation.”

That is logical and perhaps takes precedence over what we see in the haphazard third season. Perhaps.