The way it worked was you would look around your yard until you saw the raised portions of ground where the moles had created runs. You would cock the trap by pulling up on the handle at the top, which would compress the spring and raise the spikes.
After that, you would put the trap straddling the run with the big stakes on both sides, sticking it in the ground just far enough that the flat trigger at the top of the spike platform would rest across the raised dirt. The theory was that a mole passing through the run would jiggle the ground just enough to send the spikes plunging through him.
I never checked for success
I’m not sure we ever deployed the device with any serious intent to dispatch any moles, and I certainly never dug around to see if it had been successful if we had.
If you have a sadistic bent and moles in your yard, I’m pretty sure the trap ended up at Annie Laurie’s Antique Shop.
Wow! I just did a Google search for “mole trap” and came up with a whole bunch of more modern devices for dealing with the rodents. After looking at a couple of videos, I am more convinced than ever that ignorance is bliss. I’m glad I never checked for results.