Why Do Pirates Love Parrots? (22 page)

W
indows have two main jobs: to let in light and fresh air. This doesn’t seem too much to ask of a sheet of glass surrounded by a base frame, but ships pose a few extra little problems. Obviously, portholes on ships need to contend with water (windows that don’t seal properly aren’t too popular on ships, especially windows that are underwater at times). But a more pernicious danger is the movement of the boat itself.

When most ships were made out of wood, portholes were usually rectangular. But once steel construction came into vogue, sharp corners morphed into arcs. Wood may not be as hard as steel, but it has one feature that makes it more porthole-friendly: Wood absorbs the stresses of the rocking of boats on the sea far better than metal. When steel hulls came into vogue in the late nineteenth century, sailors discovered quickly that stress fractures were endemic to rectangular portholes, starting at the corners. Round portholes, on the other hand, distribute the stress evenly, and naval architects figured out the spherical solution quickly.

Rectangular portholes are far from extinct, however. Some wooden ships still have them. And cruise liners often sport large rectangular windows on decks. But the more violent the weather a boat encounters, the rougher the seas it navigates, and the farther down in the boat it resides, the more likely the porthole is to be cornerless.

Submitted by Mike Roberti of Duarte, California. Thanks also to “Carol,” via the Internet.

M
ay we exert executive privilege and pose this Imponderable, which occurred to us after researching the last Imponderable? Surely, airplane windows are subject to extreme pressures in the air. Ken Giesbers, our mole at Boeing, confirmed it:

The seriousness of the issue was highlighted when the first commercial jet, the De Havilland Comet of Britain, was plagued with three crashes shortly after its introduction in 1952. Much to their shock, thorough investigations revealed that the main culprit in all three crashes was likely metal fatigue. And most of the deterioration started at the corners of the Comet’s large, rectangular windows. The Attorney General’s report concluded that

The Comet was then redesigned with a stronger fuselage and round windows.

If round windows are best, why do Boeing and Airbus provide us with oval ones? According to Giesbers, they just aim to please:

Submitted by Dave Feldman, of Imponderables Central.

A
ll but the youngest of
Imponderables
readers will remember the little caboose, the last car on every train. Such is the appeal of that humble car that most model sets, even of contemporary trains, still feature cabooses, even though they have mostly disappeared since the early 1990s. In their stead, the back of most trains feature a skeletal open car with a flashing light.

What purpose did cabooses serve in the first place? Up until the mid-1980s, the typical freight train used to have at least four crew members. An engineer and a brakeman sat at the front in the locomotive; the other brakeman and a conductor brought up the rear in the caboose. Before the advent of radio communications, the two men in the caboose were eyes and ears for the engineer, and vital communication was handled via hand and lantern signals. Many cabooses featured cupolas, which served as observatories for the crew, who were on the alert for any sign of smoke, fire, or dragging equipment. The caboose also housed much of the train’s valuable technology, including an emergency brake, gauges to measure brake pressure, and the tools needed to make repairs to the train.

The caboose also served as a combination bedroom, office, kitchen, and bathroom as well. Many were equipped with stoves for cooking, a desk for paperwork, a latrine, and bunks for the brakemen and conductor.

Radio communication and, later, sophisticated telemetry devices eventually rendered the caboose obsolete. Perhaps the most important development in the demise of the caboose was the invention of automatic rear-end devices (usually called “FREDs” (Flashing Rear End Devices)). FREDs allowed the engineer to determine the air brake pressure from gauges on his board in front, and often to apply brakes in the back of the train—duties heretofore performed by the brakeman in the caboose. These FREDs flash the red light you see in lieu of the caboose on most trains today.

Another technological breakthrough that replaced human expertise is the Hot Box Detector (HBD), which automatically checks for overheated wheel bearings or “hot boxes.” If there is a problem, the exact axle location is automatically signaled to the engineer.

Before sophisticated telemetry, a constant challenge was ironing out the slack on long trains. In the “old days,” the conductor in back would check for slack, but now the End of Train Device (ETD) lets the engineer in front know when the back is moving—a message display on the engineer’s board lets him know.

Most states had laws mandating cabooses on trains well into the 1980s, but these slowly fell by the wayside as the big railroads convinced the Federal Railroad Administration that brakemen, and thus cabooses, were no longer needed. The motive of the railroads, of course, was financial. As Jeff Moore, webmaster of the High Desert Rails Web site (http://www.trainweb.org/highdesertrails/) put it:

Alabama locomotive engineer Jerry DeBene told
Imponderables
that it costs about $2,500 a month to maintain a caboose: “Times that by a fleet of them and you can see why they were replaced.” Some estimates for the cost of cabooses run much higher, up to six figures a year.

Although they are endangered species, neither the brakeman nor the caboose is totally extinct. On some lines, brakemen have been renamed the more generic, “trainmen.” Charlie Tomlin notes that on the Burlington Northern and Santa Fe’s Chicago division, the collector positions on commuter trains are the responsibility of brakemen and those brakemen are responsible for much of the switching: “Believe me, from having worked all of those jobs as a brakeman, there is plenty of work to do for two.”

And Jeff Moore explains the main reason why some cabooses live on amidst today’s technology:

Submitted By Douglas Watkins, Jr. of Hayward, California.

N
ope. Not even when they are nervous.

Birds don’t have sweat glands, so they can’t sweat. But they have plenty of methods to cool themselves off. Birds are warm-blooded, like we are, and their normal body temperature is actually a little higher than ours.

Although you may have never heard it, birds also pant, just like dogs, and can cool themselves off in this way. And when birds fluff up their feathers, it isn’t just to show off—fluffing allows air close to the skin so that even more evaporation occurs. These are the two most common ways that birds eliminate excess heat.

Birds are so active, and burn off so many calories while they fly about looking for food (including migrations that, for some birds, can require thousands of miles of flying), that it is a constant struggle for them to maintain the proper temperature. Hypothermia is a serious danger, so some species have developed specialized mechanisms to regulate their body temperature.

Have you ever seen the fleshy part of a bird’s bill vibrate? Herons do this most visibly, but many other species, such as boobies and roadrunners, regulate their temperatures by this “gular fluttering.” By vibrating the hyoid muscles and bones in their throat, gular fluttering achieves the same cooling effect as panting.

In
Why Don’t Cats Like To Swim?
, we discussed how penguins’ feet can withstand frigid conditions in Antarctica. But many other birds in warm climates use their feet to cool off. Martha Fischer, of Cornell Lab of Ornithology, explains:

Fischer adds that birds are believed to have evolved from reptiles, which also do not sweat:

Dinosaurs would tend to agree.

Submitted by Lorelei Truchon, of Fairfax, California.