Alex, I believe that you will find that the number you are seeing in the little window refers to a certain spring tension on the focal plane shutter.
From the looks of it, this was a single slit curtain. This means that only one size opening existed, the shutter speed based on how "wound up" the tension spring was.
On the left side of the camera (from the front) is that a ratchet I see on the inside of the big knob? Let me refer you to some information on the Graflex D series to get a better feel for how this works. You will also see great similarities to the mechanism of your camera:
Graflex is somewhat different as it used multiple slits of differing sizes along with adjustable spring tension to achieve the speed.