Ya it is a very cool lock patent Sept 29 1931.
I have Gougler one that has huge dial the entire size of the lock body with nothing on it just a chrome dial with nothing no index nothing that has to be turned all the way to the left until it stops then count clicks to the right 10 clicks then left 8 clicks then right 7 clicks then you have to pull it open. So even a blind person or someone in total darkness could use a combo lock.
This Miller has NO stop you can turn it either was all day long. Has that raised reserved dimple I can assume is the starting index to align with the arrow. But don't know which way to start counting or how many times left right left right left or right left right left right or how many clicks each time. Could be as many a 5 rotations each way. Pulling on the shackled does nothing to indicate anything. Plus the dial knob is so small with grooves on it and the spring in it is strong from click to click it is hard to turn. Trying to determine anything you will get blisters in about 30 minutes messing with it. I think that was by design to deter someone to try to figure out the combo. Somebody somewhere has the old J.B.Miller code books just haven't found them yet.
Richard