Do Penguins Have Knees? by David Feldman Page A

fact, this is the way most consumers determine whether a bulb is “dead.” Richard H. Dowhan, of GTE Products, told Imponderables that in this case you are hearing particles of a broken filament, “the most common type of bulb failure.” Barring the rare case of loose tungsten particles inside the bulb, Dowhan says “you should hear nothing when you shake a light bulb that is still capable of lighting.”
     
    Submitted by Kari Rosenthal of Bangor, Maine .
     
     
    Why Do Fluorescent Lights Make a Plinking Noise When You Turn Them On?
     
    We went to Peter Wulff again for our answer. Older fluorescent fixtures used a “preheat system,” which featured a bimetallic starter (the small, round, silver piece). Wulff told us that inside the starter is a bimetallic switch which “pings” when energized. Newer fluorescent systems, such as the “preheat” or “rapid start,” are rendering the “ping” a relic of our nostalgic past.
     
    Submitted by Van Vandagriff of Ypsilanti, Michigan. Thanks also to Kathleen Russell of Grand Rapids, Michigan; Cuesta Schmidt of West New York, New Jersey; and Walter Hermanns of Racine, Wisconsin .
     
     

     
     
    Why Do Cats Like So Much to Be Scratched Behind the Ears?
     
    Most cats like to be scratched for the same reason that most humans like to be massaged: It feels good. According to veterinarian John E. Saidla, assistant director of the Cornell Feline Health Center,
     
         Most cats like to have their total bodies rubbed or stroked by humans. A cat’s skin is chock full of nerve endings, making your stroking a sensual experience.
     
    But our skin is full of nerve endings, and not too many of us start wiggling our legs with delight when we’re scratched behind the ears. But then again, unlike cats, we don’t tend to have ear mites. Dr. Saidla explains:
     
    Most cats harbor very few mites, while others have huge infections that are causing serious clinical problems. The mite in the ear canal burrows into the layers of skin lining the ear canal. The cat is allergic, or at least, reacts to the feces and enzymes the mite produces, resulting in pruritus or itching. When the owner rubs the skin behind the ear, it feels good and the cat responds appreciatively.

Submitted by Robert J. Abrams of Boston, Massachusetts .
     
     
    Why Aren’t There Plums in Plum Pudding? And Why Is It Called a Pudding Rather Than a Cake?
     
    Even though it contains flour and is as sweet and rich as any cake, plum pudding cannot be classified as a cake because it contains no leavening and is not baked, but steamed.
    Besides flour, plum pudding contains suet, sugar, and spices and is studded with raisins and currants. In early America, both raisins and currants were referred to as “plums” or “plumbs.” And presumably because the raisins and currants were the only visually identifiable ingredients in the dessert (which traditionally was served after the pumpkin pie at Thanksgiving), the nickname stuck.
    Come to think of it, plum pudding isn’t the only weirdly named dessert served at Thanksgiving. We used to ask our parents where the meat was in mincemeat pie. * Give us an honest pumpkin pie any day.
     
    Submitted by Bert Garwood of Grand Forks, North Dakota .
     
     
    What Do the Little Red Letter and Number Stamped on the Back of My Envelope Mean?
     
    When the arm of the United States Postal System’s Multi-Position Letter Sort Machine (or, as we close friends like to call it, MPLSM) picks up an envelope, it automatically stamps a letter and number on the back. The letter identifies which MPLSM processes the piece, and the number singles out which console on the machine, and thus which MPLSM operator, handles the piece.
    This code has nothing to do with delivering the letter. The code is simply a way for the USPS to identify when a particular machine, or its operator, is malfunctioning. In other words, the A4 on the back of your envelope is the equivalent of the “Inspected by