Carpenter's Hammer?

Question

Okay I was helping my friend frame out a new addition to his house, and I grabbed one of his hammers and it had a cleft about an inch or two below the head above the handle. I was curious as to what that was for. I have never seen that on a hammer before.

Answer 1

the cleft is for putting a nail in it then with one  downward blow the nail will be  in the wood saves on fingers of people who dont nail alot  and being in a awkward position to nail when framing when you gotta use one hand to hold onto framing structure

Answer 2

Could you be a little more descriptive?  I'm a carpenter, and have seen may different hammers.  I don't know what you mean by a cleft though.  Do you know what brand it was?  More info will help.  Thanks.

EDIT:  If you are talking about a notch on TOP of the head, like the link shows, then beachedcelt has it exactly right.  You put a nail in the notch, which is also magnetic to keep it there, set the nail with a sharp blow, then drive it home.  Some people swear by it, but I prefer to hold mine the old fashioned way.  You learn after a few hits to not smash your fingers.  Hope this helps.