When Do Fish Sleep? Part 20

Several veterans, including retired Army Sergeant Robert E. Krotzer of Hephzibah, Georgia, wrote to say that they were taught that the purpose of the ball was to keep the flag from being caught on the pole when the wind blew the flag upward. The flag experts we spoke to admit that this is the reasoning the Army provides, but insist that even a sphere doesn't stop a flag from getting stuck on top of a pole.

On Why the Sound of Running Water Changes When Hot Water Is Turned On I do not deny the validity of the causes you discussed, however the pitch of that sound at a given rate of flow depends on the density of the water. Hot water is substantially less dense than cold water.... The fundamental fact of physics is that different density fluids have different natural frequencies of vibration while flowing through a given orifice.

Just turn on any hot-water faucet that has been off long enough for the water content to get cold some distance down the pipe. Then stand back and listen. You will clearly hear a change in pitch as the hot water arrives. The change is sudden and cannot be explained by any adaptive change of the pipes. It is the direct result of the change in the natural frequency of the water itself. The noisier the flow the more noticeable the change.

STEFAN HABSBURG.

Farmington Hills, Michigan

On Why We Aren't Most Comfortable in 98.6 F Temperature In Why Do Clocks Run Clockwise?, you wrote we would feel most comfortable when it is 98.6 F in the ambient air-if we were nudists.

Not exactly so. Human beings use up caloric energy, derived from food, to make motions with our muscular bodies. This process yields a certain amount of excess energy in the form of heat. Our bodies radiate this excess heat into the ambient air. When severely overheated, our bodies hasten the action by evaporating sweat. But we must have a means to keep our body temperature at 98.6 F or we die of heat prostration.

If we were all nudists and the ambient air everywhere was 98.6 F, we'd feel discomfort the moment we began to move. Lacking a temperature differential in the ambient air, our bodies could no longer radiate heat easily. First we'd sweat, and then we'd all die.

The only hope to remain alive would be to remain as motionless as possible for as long as possible, but sooner or later the excess heat from involuntary motions (like the heart and lung muscles) would build up.

So a 98.6 F temperature wouldn't be "comfortable" very long.... We need a slightly lower temperature in the air sooner or later.

DON SAYENGA.

Bethlehem, Pennsylvania

On Bird Droppings You can't get away with anything with Imponderables readers. We simplified a little by calling the white stuff surrounding the black dot in bird droppings "urine." One reader noticed.

Mammals and amphibians get rid of nitrogenous waste in the form of urea dissolved in water. This is the material we commonly call urine. Birds and reptiles cannot accomplish this. They get rid of their nitrogenous wastes in a white semisolid form called uric acid. This is the white material in the birds' droppings.

There are two reasons why birds and reptiles use uric acid for waste disposal. One is because it is a water conservation technique. The other reason is perhaps more important. Bird and reptile embryos develop inside a hard sh.e.l.l. If they were to produce water-soluble urea while developing, it would end up poisoning the embryo before it could fully develop and hatch.

This leads us to the answer of another interesting question, "What is that 'gooky' stuff inside the sh.e.l.l after a baby bird hatches?" It is the remains of what is called the "allantois," the garbage can where nonsoluble uric acid is deposited while the embryo is developing.

SANDY JONES.

Mana.s.sas, Virginia

On the Purpose of the Half Moons on Fingernails Although our explanation-lunula are trapped air and serve no biological purpose-was correct, one reader did find a way to use them: When preparing a patient prior to surgery requiring a full anesthetic, I was told to remove all nail polish prior to admission. When I asked why, I was told that recovery room personnel can monitor blood pressure by observing changes in the color of half moons.

MICHEALE WILLIAMS.

Portland, Oregon

On the Mysterious Fruit Flavors Contained in Juicy Fruit Gum When I was in college, I made the synthetic flavors of oil of pineapple (ethyl butyrate) and oil of banana (amyl acetate). I found when mixed in precisely a certain ratio, I got the distinct aroma of Juicy Fruit....

Incidentally, if one wishes to synthesize ethyl butyrate, be prepared. Butyric acid is one stinking, sickening smelling acid. But once mixed with ethyl alcohol and concentrated sulfuric acid, the ethyl butyrate emerges with a sweet pineapple aroma.

HAROLD E. BLAKE.

Tampa, Florida

On the Purpose of Pubic and Underarm Hair Most of the experts we contacted speculated that this body hair served as a s.e.xual attractant. But in a letter to Human Evolution, one reader dissented. We reprint part of the letter with his permission: Public and axillary hair have been a.s.sumed to be biologically non-functional and therefore relegated to a role of mere s.e.x attractants or to signal s.e.xual maturity. Yet if one examines the action of axillary and pubic hair it can be seen that these patches serve as a kind of lubricant for arm and leg movements repectively and must have been retained in that capacity or evolved separately when other body hair was lost. One can easily observe the friction-reducing function of axillary hair by shaving under one arm and noting the added friction of the shaved arm. The fact that pubic hair extends up the abdomen beyond the point where it facilitates leg movement may mean that body hair was lost while our forebears were still walking in a crouch or on knuckles; for it comes into function, particularly the lateral portions, in that position. It would serve well for a semicrouched or sometimes-crouched proto-hominid that had lost most of its body hair. As our ancestral mothers began losing their body hair, fatty b.r.e.a.s.t.s and pubic and axillary hair could have all evolved simultaneously. The hair patches were selected for the purely biological function of reducing friction whereas general loss of body hair gave rise to the necessity of fatty b.r.e.a.s.t.s for providing the crucial psychological role of softness, comfort, and security for the infant.

NOEL W. SMITH.

State University of New York

Plattsburgh, New York

On Why Ranchers Hang Old Boots Upside-down on Fence Posts The longest chapter in Why Do Clocks Run Clockwise? was a futile attempt to answer this Imponderable. We confirmed that Nebraska was the epicenter of boot-hanging activity. We even found the son of the man reputed to have started the practice. But even he didn't know why his father hung the boots. Some readers had their own ideas.

Marla Bouton, of Kearney, Nebraska, sent us an article by Roger L. Welsch, professor of English and anthropology at the University of Nebraska-Lincoln, published in the October 30, 1983, Sunday World-Herald Magazine of the Midlands. Along with repeating all of the theories we advanced, Welsch recounted many other stories he was told by boot-hangers, including the number of boots indicated the number of sons in the family; the toes point toward the nearest graveyard; the toes point toward the main house in case someone was lost in a snowstorm; and the boots are a token of good luck.

Welsch concludes that although there may not be one single answer, hanging boots is probably some form of territorial marker. He notes that boot hanging is most prevalent in arid flatlands.

In a geography like this, long arrays of boots are striking, even stunning, and that is precisely their purpose. They are markers. They announce that someone lives here in this moonscape, that there are inhabitants, no matter how "deserted"-a perfect word, "deserted!"-things appear to be....

Several readers insisted there was a more practical explanation for the custom.

The ranchers may be trying to stop the absorption of water.... In Alabama, a lot of farmers turn empty cans onto the tops of fence posts for this reason, or they will nail the tops that were taken from cans, onto the tops of the posts. This keeps the posts from absorbing large amounts of water when it rains. Wooden posts absorb quite a bit of water through the tops. Putting boots on the posts might prevent the wood from rotting prematurely.

C.A. "JUNIOR" WEAVER

Millbrook, Alabama

In West Virginia, some of the older farmers, including my grandparents, used to put on tin cans, old pieces of tires, roof s.h.i.+ngles, or something else that would cover the top and hand down the sides of the fence posts.

This practice was done mostly to fence posts that still had bark on them. The farmers felt there was no reason to put objects on posts that had the bark stripped off.

Still asking why? Believe it or not, the reason was to keep the fence posts from rotting.

The idea was to keep the rain and snow from laying on the top of the post and soaking or running behind the bark. They believed the rain or snow would run down behind the bark, become trapped and rot the wood faster than if there was no bark at all on the posts....

My husband and I have fence posts in our backyard (they are over 10 years old) and the bark has been stripped off. They show no signs of rot so far. They are so hard you can't hardly drive a nail into them.

Every once in awhile when I am traveling on some of the older, less busier country roads in the state, I see a fence with something on the top of the fence posts, and I remember asking my grandfather why he was doing it. I am glad that I was curious enough to ask because I may have helped you solve an Imponderable that seemed to be driving you nuts.

ELAINE K. SOUTHERN.

Clarksburg, West Virginia

If most of our letters on this subject came from the South and the Midwest, we received at least one sighting considerably farther to the north.

I was very surprised to see this in your book as I thought this practice was only done in my old territory.

I was a district rep for a car manufacturer and my territory included the central east of Alberta, Canada. This included Drumh.e.l.ler and Trochu, two small towns on either side of the Deer River.

Drumh.e.l.ler is famous for being the site of one of the first large dinosaur finds in North America. It now has a large scientific museum that attracts thousands of visitors every year. Trochu is not famous for anything, although it does have a very good ice-cream stand open during the summer.

Anyway, the back road from Drumh.e.l.ler to Trochu is one of the most pleasant drives you can find on the prairie....

After crossing the river and driving toward Trochu and the ice-cream stand, there is a rancher who has put hundreds of boots on his fencing along the road. I asked about them and was told that they were to stop the aging of the fence posts. If the tops of the posts are covered and not left exposed, they will last that much longer. And since I once had a job replacing an old fence, I can a.s.sure you that anything that can be done to make them last longer would be tried.

KEVAN TAYLOR.

Niagara Falls, Ontario, Canada

Acknowledgments.

The single most gratifying part of my job is receiving the thousands of letters that readers of Imponderables have sent me. Your ideas have supplied most of the mysteries answered in this book. Your support and encouragement have supplied the inspiration.

I have kept my promise to answer all letters that have included self-addressed stamped envelopes. I'll continue the practice, but please be patient. When deadline pressure mounts, so does my response time. I cherish your letters and pounce on each one like a child encountering a wrapped birthday present.

In Harper & Row, I have a found a publis.h.i.+ng house that provides me with all the benefits of a family-without the in-laws. Excepting that he is taller and wears clothes better than me, Rick Kot is all I could ask for in a person or an editor. His a.s.sistant Scott Terranella is exhibiting annoying tendencies toward becoming as perfect as Rick, but Scott has been so kind to me it's hard to get mad at him.

From the top down the folks at Harper & Row have been gratuitously nice to me. The publisher, Bill s.h.i.+nker, has been constantly supportive and enthusiastic. The beloved Brenda Marsh and the sales reps (sounds like a Motown act!) have, wonder of wonders, gotten my books into the stores. Roz Barrow, with skill and graciousness, made sure there were enough books to s.h.i.+p to the stores. Steve Magnuson has been full of great marketing ideas. Debra Elfenbein, with a sharp mind and several sharp red pencils, helped tighten and focus this ma.n.u.script. The publicity department, headed by Karen Mender, helped thrust me upon an innocent North America. Special thanks to my publicist and rock 'n' roll heartthrob, Craig Herman, and to Allison Koop, Susie Epstein, and Anne Berman. And to the trinity in Special Markets, Connie Levinson, Barbara Rittenhouse, and Mark Landau: You have a friend for life, whether you like it or not.

In Why Do Clocks Run Clockwise?, I complained that my agent, Jim Trupin, didn't laugh enough at my jokes. I'm happy and proud to announce that he has corrected this egregious flaw and can now lay claim to be the last Renaissance man. Jim and his wife, Elizabeth, are two of my favorite people. Speaking of favorite people, Ka.s.sie Schwan, ill.u.s.trator and semiprofessional gardener, continues to produce terrific ill.u.s.trations. And the late (not dead, just late) Mark Kohut has taught me more than anyone about how the book business works. Lovely Joann Carney is the only person who has ever gotten me to sit in front of a camera for more than five minutes without wiggling uncontrollably, let alone to enjoy the process of being photographed.