Interesting find. However, what makes you certain it's a Keuffel & Esser Co transit, though? I've located several other brands that looks quite similar and I cannot make out enough detail on the compass to tell (most have the company name on the compass).
As with most of these “real world” props, you’re absolutely right, it’s hard to be 100% certain of a specific make and model. In this case it’s also complicated by the fact that these transits were manufactured for many years in the early 1900s, which could result in minor differences in the same model year-over-year.
Mine is supposed to arrive tomorrow, so I will be able to match parts with the screen captures with more certainty once I can put the actual model in the same position as the screen used caps. I will post more pictures with a more detailed part by part analysis then.
For now, I’m about 90% sure that the model used in the movie was a K&E Railroad Transit for a couple of reasons.
1. The ‘U’ shaped mounting brackets are one of the biggest differences between other models and manufacturers. Many others (including the Brandis& Sons that you mention above) have cross bars and different attachment pieces where the transit mounts to the actual bracket.
2. Many transits (even in the K&E line) are much shorter in length than the Railroad transit. When you compare the screen grabs, you can see based on HF’s head and hands for scale, that it’s rather long.
3. The eye piece and opposite end have distinctive shapes. These are consistent with the Railroad transit.
4. The various screws and attachments on the scope itself and also the levels on the compass part are in distinctive spots that match the railroad transit. (This is another key difference in a lot of the other manufacturers.)
5. The location of the attachment of the smaller “tube” to the scope, combined with the placement of the focus knobs was a key indicator and difference between models. (Again, you can really see this when you compare it to the Brandis & Sons picture above. The tube attaches almost at the eye piece, where on the screen captures you can see it attached a few inches in - more in the middle of the scope.)
Like I said, I’m still not even 100% sure, but hopefully having the actual model in hand and being able to post comparisons with it in the same angle as the screen captures will increase that certainty. Also, as I mentioned - I did consult with a few antique surveying equipment experts who were actually the ones who pointed me in the direction of K&E in the first place just based on the movie screen grabs I sent them.
Also, like you pointed out, these things were very modular, they could be ordered in a number of configurations with lots of variation. The likelihood of any one of us happening to find the exact same configuration used in the movie is pretty slim (but that’s never stopped us from trying before!) As you said, it’s up to each collector to decide how “close” is close enough for your collection.
Hopefully soon I’ll be able to post some more convincing evidence with photo comparison proof.