When this turned up in a box of stuff on Frank Hoban's table, I just had to have it:
The black sleeve over the barrel is spring loaded and slides down the barrel:
So if you want to know the sum of six and eight, set the discs at the top to "00", then pull the black sleeve down to the six mark, release, then pull it down to the eight. As you pull, the discs rotate to give you the result:
Quite the Rube Goldberg contraption, isn't it? Although the pencil is unmarked, I suspect I've got a clue as to who may have made it. Here it is shown alongside the Houk Adding Pencil, which I covered in an article on December 21:
OK, I know. Both are adding pencils -- duh -- right? But there's some design details common to both of these that lead me to believe both of these were made by Houk. First off, notice that the Houk is not marked on the pencil itself; the only way we know who made it is the paper label on the lower barrel. Next, look at the ferrules:
Notice that little rib just where the barrel meets the tip? And at the other end:
Both have two knurled ribs. There's no question in my mind that the new addition is another version of the Houk Adding Pencil.