Do Penguins Have Knees? (28 page)

Maybe. But will the supermarkets redeem them?

Why
Do Only Female Mosquitoes Eat Human Blood? What Do Male Mosquitoes Eat?

No, the mosquito menfolk aren’t out eating steak and potatoes. Actually, the main food of both male and female mosquitoes is nectar from flowers. The nectar is converted to glycogen, a fuel potent enough to provide their muscles with energy to fly within minutes of consuming the nectar. Mosquitoes also possess an organ, known as the fat-body, that is capable of storing sugar for conversion to flight fuel.

Male mosquitoes can exist quite happily on a diet of only nectar, and nature makes certain that they are content—males don’t have a biting mouth part capable of piercing the skin of a human. But females have been anatomically equipped to bite because they have an important job to do: lay eggs. In some species, female mosquitoes are not capable of laying any eggs unless they eat a nutritional supplement of some tasty, fresh blood. Their organs convert the lipids in blood into iron and protein that can greatly increase their fecundity.

A mosquito that would lay five or ten eggs without the supplement can lay as many as 200 with a dash of Type O. Although we don’t miss the blood sucked out of us, this is quite a feast for the mosquito; many times, she consumes more than her own body weight in blood.

But let’s not take it personally. Some studies have indicated that given a choice, mosquitoes prefer the blood of cows to humans, and in the jungle are just as likely to try to bite a monkey or a bird as a human.

If
the Third Prong on an Electrical Plug Is for Grounding and Shock Protection, Why Don’t All Plugs Have Three Prongs?

In the good old days, electrical plugs had two prongs and the receptacles were ungrounded. If you happened to use the wrong side of the circuit, it could be a shocking experience. So a simple and effective idea was developed: add a third prong. Don French, chief engineer for Radio Shack, explains the principle:

Meanwhile, however, other engineers were working on “double insulated” prongs that do not require a third prong for protection. Although the third prong was rendered unnecessary, most old receptacles weren’t wide enough to receive the fatter prongs—another example of incompatible technologies that benefited the manufacturers (think of all the consumers who had to refit receptacles and buy new extension cords to hold double insulated prongs) and bankrupted the consumer.

Why
Does Menthol Feel Cool to the Taste and Cool to the Skin?

Of course, the temperature of menthol shaving cream isn’t any lower than that of musk shaving cream. So clearly, something funny is going on. R. J. Reynolds’s public relations representative, Mary Ann Usrey, explains the physiological shenanigans:

Why
Do Bridges Freeze Before Nearby Roads?

Asphalt, used in most roads, retains heat better than bridge decks, which are usually made out of concrete slabs. But the most important reason has more to do with elementary physics. Stanley Gordon, chief of the Bridge Division of the Federal Highway Administration, explains:

In other words, the earth itself provides insulation to roads. Any heat that accumulates in the bridge during the day will be released as the ambient temperature drops. As Amy Steiner, program director for the American Association of State Highway and Transportation Officials, put it, “Bridge decks can release only heat absorbed by the deck itself and obviously do not benefit from the heat retained by the soil.”

Why
Can’t They Make the Flavor in Chewing Gum Last Longer?

Call us paranoid, but we always suspected that gum manufacturers attended trade seminars on such subjects as “The Enemy: Long-Lasting Flavor,” “How to Make Sure Your Customers’ Chewing Gum Loses Its Flavor on the Bedpost Overnight,” and “How to Make Your Gum Tasteless Before Your Sucker Customer Has Thrown Away the Wrapper.” Emboldened by such rhetoric, the gum makers see dollar signs floating above their eyes and produce gum whose flavor lasts less time than a Zsa Zsa Gabor marriage. Naive consumers are then confronted with the imperative of plopping another stick of gum into their mouths to receive the flavor jolt they received all of, maybe, three minutes ago.

But industry folks insist that the conspiracy theory just isn’t true. In fact, Bill O’Connor, director of administration at the Topps Company, told
Imponderables
that if a company could create a gum that retained flavor longer, it would hammer this competitive advantage home in advertisements. Wrigley’s has done just that with its Extra gum, which uses “encapsulation,” little flavor pockets that require more mouth action than conventional gum to draw out its flavor. In essence, Wrigley created a time-release gum.

But even encapsulation doesn’t beat the two main enemies of flavor retention in chewing gum:

O’Connor suggests that if you put aside a “used” piece of gum, eat a saltine to cleanse the palate, and then plop the gum back into your mouth, it will taste flavorful again.

May we suggest an alternative: plopping a new stick of gum in your mouth.

What
Is the Purpose of the Plastic Bags in Airline Oxygen Masks When They Don’t Inflate?

We’re always amazed when we find out that an airplane has been evacuated successfully during an emergency landing. The airlines try to do a good job briefing passengers on the safety requirements before takeoff. But a quick scan of the passengers will indicate that the seasoned fliers are already napping or deeply engrossed in the scintillating inflight magazine, while the less experienced tend to be hanging on every word, in a panic, trying to conjure in their minds how they can convert their seat cushion into a flotation device.

We tend to combine the worst aspects of both types of passengers. We attempt to read our newspaper, having heard the announcement 80 million times, but we’re actually trying to suppress our fear that there aren’t
really
oxygen masks up there that are going to drop down during an emergency.

All white-knucklers are familiar with the proviso in the safety demonstrations of oxygen masks: “Although the bag won’t inflate, oxygen is still flowing…” or the variant, “Although the bag will not
fully
inflate…” Several sharp
Imponderables
readers have wondered: If the bag doesn’t inflate, why does it have to be there? Our image of an oxygen bag comes from
Ben Casey
, where resuscitators inflated, deflated, and reflated as violently as a fad dieter.

But the bag does serve a purpose. Honest. The mask used by airlines is called a “phased-dilution” mask. As you inhale, you are breathing in a mixture of ambient air and oxygen. Compressed oxygen is quite expensive, and particularly at low altitudes, you actually need very little pure oxygen even if the cabin is depressurized.

A nasty little secret is that a bizarre cost-saving device, the “oxygen mask” used in safety demonstrations, is not the real thing (if you look carefully, on most airlines, the mask will be marked “DEMO”) and isn’t even an exact replica. The real oxygen mask contains three valves that are the key to regulating your breathing in an emergency. The first, interior, valve pumps in pure oxygen. When the oxygen is depleted, the valve closes and the second, exterior valve opens and brings in ambient air (thus the term “phased-dilution”). The third, external valve, with a spring device, opens only to allow you to vent your exhalation.

According to oxygen equipment expert David DiPasquale, an engineer and administrative and technical consultant and major domo at DiPasquale & Associates, the normal cabin pressure is set to simulate the atmosphere of approximately 8,000 feet. The oxygen system automatically adjusts to different altitudes, varying the flow of oxygen. The higher the altitude, the higher percentage of oxygen (to ambient air) and the faster the flow rate of oxygen is required. During decompression, a plane may suddenly find itself at an atmosphere equivalent to the ambient air at 35,000 feet or higher.