Seth Thomas Mantle mystery

I just found this at a 2nd hand store, It works very well and I'm going to clean inspect and oil it. (I now how its ok) but first S&T. The face says patent applied, not patent 1880 like I've seen others with the alarm option, I've never seen the housing before on google or ebay. No stamped numbers anywhere. Any help would be awesome, I'm just a hobbyist right now but will get a little more into them when I move. (I'll have a workshop then.) I do cuckoos this is only the second mantle one I have. Thanks in advance!! Kathy
Oh I know it says it's a adamantine its on the back cover if thats its cover.