How Does Aspirin Find a Headache? (12 page)

Why
Is It That What Looks to Us Like a Half-Moon Is Called a Quarter-Moon by Astronomers?

An intriguing Imponderable, we thought, at least until Robert Burnham, editor of
Astronomy
, batted it away with the comment, “Aw, c’mon, you picked an
easy
one this time!”

Much to our surprise, when astronomers throw lunar fractions around, they are referring to the orbiting cycle of the Moon, not its appearance to us.
Sky & Telescope’s
associate editor, Alan M. MacRobert, explains:

Robert Burnham adds that “quarter-Moons” and “half-Moons” aren’t the only commonly misnamed lunar apparitions. Laymen often call the crescent moon hanging low in the evening sky a “New Moon,” but Burnham points out that at this point, the moon is far from new: “In fact, by then the crescent Moon is some three or four days past the actual moment of New Moon, which is the instant when the center of the Moon passes between the Earth and Sun.”

What’s
the Deal with the Grades of Architectural and Art Pencils? What Do “H,” “HB,” “F,” “B,” and “E” Stand For?

Here’s the code: “H” stands for Hardness and “B” stands for “Black.” With pencils, “hard” means a pencil that yields a lighter image. “Soft” pencils provide darker images. In this case, “black” means soft.

From hardest to softest, these are the grades: 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, H, HB, F, B, 2B, 3B, 4B, 5B, 6B.

HB is the equivalent of the “regular” number 2 pencil. The grade “F” is a grade between “HB” (hard and black) and “B.” Ellen Carson, of pencil manufacturer Empire Berol USA, told us that “F” was originally introduced for taking shorthand, because it was “hard enough to withstand extended use without resharpening and black enough so as to ensure that the shorthand was subsequently legible.”

The “E” grades are used to designate the hardness of Filmograph leads. According to Carson, these leads are produced for plastic film and used in technical drawing. Filmograph leads contain no graphite and are based upon polymers and carbon black: “They are used in order to prevent the written or drawn line from being smudged when the drawing is being handled.” E1 is the softest grade and E4 the hardest.

How
Do Hermit Crabs “Relieve Themselves” When in the Shell Without Getting Filthy? Or Do They Get Filthy?

The last few chapters have been altogether too pleasant. We don’t want you to get complacent; it’s time for a real gross-out now.

We often hear the bromide about the perfection of Mother Nature—that everything is part of her plan. But she had some strange plans in mind when she created the hermit crab. A “hermit crab” is not a particular species or family of crab; the term refers to various crabs that have soft abdomens and live in the empty shells of mollusks. The vision of a crab living in a vacated snail shell isn’t too appetizing to begin with; but combine it with the crustacean’s questionable bathroom habits, and we are stuck with one unpleasant visual image.

We asked one of our favorite crustacean experts, Dr. Darryl Felder, chairman of the biology department at the University of Louisiana, Lafayette, to explain our Imponderable. Even this expert couldn’t remain clinical:

Not content to render an expert opinion on such a weighty subject alone, Dr. Felder was kind enough to pass along our query to Dr. Rafael Lemaitre, a research zoologist at the National Museum of Natural History at the Smithsonian Institution. Dr. Lemaitre concurred with all of Dr. Felder’s conclusions but was kind enough to provide even more repellent details:

Lemaitre adds that the hermit crab can, by itself, create the currents necessary to flush the wastes out of its system. And if its plumbing fails, and it gets too grubby for the crustacean, it can always do what is most characteristic of a hermit crab: Ditch the shell it’s living in and find more pristine accommodations elsewhere.

Why
Does Getting a Hair in Our Mouth Make Us Gag?

Our correspondent, Ilona Savastano, was passionate in her need for an answer to this burning Imponderable:

We flew your question by our dental experts, who are used to patients gagging (sometimes even
before
they receive their bill).

Their first reaction was to emphasize the sensitivity of the mouth. Dentist Ike House, of Haughton, Louisiana, amplifies:

Now that we have established how sensitive our mouths are, we might ask whether there is anything particularly nasty about the hair itself that might cause particular problems if found in the mouth. Yes, indeed, insist our experts. Dentist Barnet Orenstein, of the New York University David B. Kriser Dental Center, explains:

The gag reflex isn’t necessarily more likely to occur when the mouth is full than when it contains one lonely hair. We can be tickled more easily by the light touch of a feather on the neck than by a hard rubbing of a bulkier object.

But the main culprit in hair-gagging is well above the throat. All of our dental experts think that the main cause of hair-gagging is psychological.

Dr. House reports that he has often been able to decrease or eliminate a patient’s gag reflex simply by talking to him or her about the problem. And he opines that the nature of a foreign body determines our reaction to it:

So buck up, Ilona. Sure, you may not be able to control your gag on a single stand of hair, but blame the messenger, not the message. Gagging can be good for you, as Dr. Orenstein explains:

Why
Does Pasta Create Foam When Boiling?

Pasta is made from durum wheat, a particularly hard wheat. More precisely, pasta is created from durum wheat
semolina
, fine particles derived from the much coarser durum. The extraction of the semolina is largely responsible for the foaming of pasta when cooking, as Farook Taufiq, vice-president of quality assurance at Prince Company, explains: