Ryan had a question:
Use your right hand. Make a small circle with your thumb and forefinger, with your other fingers parallel to your forefinger. This is a hand horn. You play it by buzzing your lips on the circular aperture.
This technique was invented by Hampl and brought to perfection by Punto. The success of this technique is keenly sensitive to the position of your hand. If, for example, you also play fr**ch horn, it is generally advisable to take your hand out of the bell first, unless, of course, you have an unusually small head.
Unfortunately, after Punto's death, the hand horn technique went into decline. Since players could not support themselves by performing, they supported themselves as petty thugs and pickpockets. Purists, however, felt that the aesthetics of the instrument was spoiled by relying on such low crooks.
Of course, the hand horn is highly appropriate in music by Handel, such as the Water Music. Some modern players, however, have performed this piece using side vents, or "carpal tunnels." Other authorities argue that this method is inauthentic. Still others believe that the whole issue has gotten out hand.
I trust this explanation will dispell any feelings of certainty that may have been troubling you.
Gotta go,
Prof. Cabbage