Do Penguins Have Knees? (22 page)
Read Do Penguins Have Knees? Online
Authors: David Feldman
So the real question is why auto manufacturers don’t design their back windows to go down all the way. C. R. Cheney, of Chrysler’s Engineering Information Services department, wrote to us about this decision:
With the advent of automotive air conditioning, the need for this feature disappeared, since it was no longer necessary to promote maximum flow-through ventilation in this way (at one time, windshields could be opened, too). We can also probably make a good case for improved safety in vehicles with a fixed rear window because this area can no longer be a path of entry for exhaust fumes, insects that could distract the driver, noise, etc.
Of course, occupants of a car are as worried about what might go
out
of a car as what might traipse in. Max E. Rumbaugh, Jr., vice-president of the Society of Automotive Engineers, wrote that
Some engineers in the past have been known to limit the downward movement of rear windows in the belief that customers want protection that prohibits young children from climbing out of a wide open rear window while a vehicle is moving down a highway.
And all things being equal, why wouldn’t manufacturers design a rear window so that customers could put the window down as far as they want? Rumbaugh explains:
…Some engineers may be faced with constraints caused by the design and manufacture of a smaller car. In smaller cars, the location of the rear wheel dictates the shape of the rear door. This shape can force a restriction on the downward movement of a full-size rear window.
Submitted by Joanne Walker of Ashland, Massachusetts. Thanks also to David A. Kroffe of Los Alamitos, California; Stephanie Suits of San Jose, California; and Renee Tribitt of Minot, North Dakota
.
What
Is the Two-Tone Signal at the Start of Many Rented Videotapes?
Yes, it has a purpose other than to puncture your eardrums. Or at least that’s what several videotape experts have claimed, anyway.
William J. Goffi, of Maxell Corporation, told
Imponderables
that the tone
is used to facilitate the recording and loading process of videotapes. As the videotapes are duplicated on high-speed duplicators, the tone “tells” the machine to either stop or start the duplicating process. As the tape is loaded into the shells, the tone again “tells” the loader where the tape starts and ends.
Not all professional duplication is done on high-speed machines. Some production houses duplicate in real time, with one “master” machine supplying the material for dozens of “slave” copying machines. According to Panasonic’s public relations manager, Mark Johnson, the two-tone signal is also used to set the audio levels for the slave machines.
All we know is that the two-tone signal sure doesn’t help us set the proper volume level on our television. Nothing can sell us on the idea of a remote that can set volume levels more than a trip up to the TV set to turn down the shrieking blast of the two-tone frequency (which only a dog could love). Inevitably, we follow up with a weary trek, fifteen seconds later, to turn up the sound so that our witty comedy doesn’t turn out to be an unintentional mime show.
Submitted by Cary Chapman of Homeland, California
.
How
Was 911 Chosen as the Uniform Emergency Telephone Number?
Old-timers like us will remember when the codes for telephone services were not uniform from city to city. In one town, “information” could be found at 411; in another, at 113. The Bell system needed to change this haphazard approach for two reasons. Making numbers uniform throughout the country would promote ease of use of their services. And reclaiming the 1 as an access code paved the way for direct dialing of long-distance calls.
Most of AT&T Bell’s service codes end in 11. 211, 311, 411, 511, 611, 711, and 811 were already assigned when pressure accumulated to create a uniform, national number for emergencies. According to Barbara Sweeney, researcher at AT&T Library Network Archives, all the numbers up to 911 had already been assigned. So 911 become the emergency number by default.
Think of how sophisticated the automated routers of the phone system are. When you dial 411 for directory assistance, each digit is crucial in routing the call properly. The first digit, 4, tells the equipment that you are not trying to obtain an operator (“0”) or make a long-distance call. The second and third digits, 11, could be used in an area code as well as an office code, so the equipment has to be programmed to recognize 211, 311, 411, 511, 611, 711, 811, and 911 as separate service codes and not “wait” for you to dial extra digits before connecting you with the disconnected recording that will tell you the phone number of Acme Pizza.
Submitted by Karen Riddick of Dresden, Tennessee
.
Why
Do Birds Bother Flying Back North After Migrating to the South?
Why bother flying so many miles south, to more pleasant and warmer climes, only to then turn around and trudge back to the only seasonably hospitable northeastern United States? Come to think of it, are we talking about birds here or half the population of Miami?
We’re not sure what motivates humans to migrate, but we do have a good idea of what motivates birds to bother flying back north again. Of course, birds probably don’t sit around (even with one leg tucked up in their feathers) thinking about why they migrate; undoubtedly, hormonal changes caused by natural breeding cycles trigger the migration patterns. After speaking to several bird experts, we found a consensus on the following reasons why birds fly back to the North:
1.
Food
. Birds fly back north to nest. Baby birds, like baby humans, are ravenous eaters and not shy about demanding food. As Todd Culver of the Laboratory of Ornithology at Cornell University put it, “The most likely reason they return is the super abundant supply of insects available to feed their young.” The more food the parents can raise, the healthier the offspring will be and the lower the babies’ mortality rate.
2.
Longer daylight hours
. The higher the latitude, the longer period of daylight parents have to find food and feed it to their babies. Some birds find food sources solely by using their vision; they cannot forage with any effectiveness in the dark.
3.
Less competition for food and nesting sites
. If all birds converged in the southern latitudes when nesting, it would be as easy to find a peaceful nest and plentiful food sources as it would be to find a quiet, pleasant, little motel room in Fort Lauderdale during spring break.
4.
Safety
. Birds are more vulnerable to predators when nesting. In most cases, there are fewer mammal predators in the North than in the South. Why? Many mammals, who don’t migrate, can’t live in the North because of the cold weather.
5.
Improved weather
. Some birds migrate south primarily to flee cold weather in the North. If they time it right, birds come back just when the weather turns pleasant in the spring, just like those humans in Florida.
Submitted by Michael S. Littman of Piscataway, New Jersey. Thanks also to Jack Weber of Modesto, California; Lori Tomlinson of Newmarket, Ontario; and Saxon Swearingen of La Porte, Texas
.
Why
Are the Oceans Salty? What Keeps the Oceans at the Same Level of Saltiness?
Most of the salt in the ocean is there because of the processes of dissolving and leaching from the solid earth over hundreds of millions of years, according to Dr. Eugene C. LaFond, president of LaFond Oceanic Consultants. Rivers take the salt out of rocks and carry them into oceans; these eroded rocks supply the largest portion of salt in the ocean.
But other natural phenomena contribute to the mineral load in the oceans. Salty volcanic rock washes into them. Volcanos also release salty “juvenile water,” water that has never existed before in the form of liquid. Fresh basalt flows up from a giant rift that runs through all the oceans’ basins.
With all of these processes dumping salt into the oceans, one might think that the seas would get saturated with sodium chloride, for oceans, like any other body of water, keep evaporating. Ocean spray is continuously released into the air; and the recycled rain fills the rivers, which aids in the leaching of salt from rocks.
Yet, according to the Sea Secrets Information Services of the International Oceanographic Foundation at the University of Miami, the concentration of salts in the ocean has not changed for quite a while—about, oh, 1.5 billion years or so. So how do oceans rid themselves of some of the salt?
First of all, sodium chloride is extremely soluble, so it doesn’t tend to get concentrated in certain sections of the ocean. The surface area of the oceans is so large (particularly since all the major oceans are interconnected) that the salt is relatively evenly distributed. Second, some of the ions in the salt leave with the sea spray. Third, some of the salt disappears as adsorbates, in the form of gas liquids sticking to particulate matter that sinks below the surface of the ocean. The fourth and most dramatic way sodium chloride is removed from the ocean is by the large accumulations left in salt flats on ocean coasts, where the water is shallow enough to evaporate.
It has taken so long for the salt to accumulate in the oceans that the amount of salt added and subtracted at any particular time is relatively small. While the amount of other minerals in the ocean has changed dramatically, the level of salt in the ocean, approximately 3.5 percent, remains constant.
Submitted by Merilee Roy of Bradford, Massachusetts. Thanks also to Nicole Chastrette of New York, New York; Bob and Elaine Juhre of Kettle Falls, Washington; John H. Herman of Beaverton, Oregon; Matthew Anderson of Forked River, New Jersey; and Cindy Raymond of Vincentown, New Jersey
.
How
Do 3-D Movies and 3-D Glasses Work?
3-D movies are a variation of the stereovision systems (e.g., Viewmasters) that we see used in tourist trinkets and children’s toys. These devices present two different views a few inches apart from the viewpoint of the human eyes. The left image is presented only to the left eye and the right image is sent directly to the right eye.
But the technology for a 3-D film is more complicated, because the filmmaker must invent some way to keep the left eye from seeing what only the right eye is supposed to view, even though both images are being projected on the screen simultaneously. The history of the technology was reviewed for us by David A. Gibson, of the Photo Equipment Museum of Eastman Kodak Company:
The first system was invented in the 1890s, and the images are called anaglyphs. The left-eye image was projected with a red colored filter over the projector lens and a blue-green filter [was put] over the lens of the projector for the right-eye image. Glasses with the same color filters were used in viewing the images—the red filter for the left eye transmitted the light from the left-image projector, and blocked the light from the right-image projector. This system has also been used to print such things as stereo comic books and has been used experimentally with stereo images broadcast on color television.
