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The rate at which crickets chirp depends also on the species, but a good average is about a chirp a second when the night air is fifty-five degrees. If you want to be a show-off at your next scout meeting or Trivial Pursuit game, you can tell everyone that the name for the relationship between temperature and chirping is Dolbear’s law.
Amos Dolbear, born in 1837, was almost the world’s most famous person. And not because of insects. When we think of the invention of the telephone, radio, and electric light, the names Bell, Marconi, and Edison spring to mind. But for a whisker of chance it would have been—some say it should have been—Dolbear alone.
He was no toolshed tinkerer. Amos Dolbear graduated from Ohio Wesleyan University and ultimately became chairman of the physics department at Tufts University. While still in his twenties he created a working telephone that he called a talking telegraph, a device that used his own receiver constructed of a permanent magnet and a metallic diaphragm. This was in 1865, fully eleven years before Alexander Graham Bell patented his version of the telephone. Later, Dolbear tried strenuously to show that he and not Bell was first, and the case went all the way to the United States Supreme Court. The journal Scientific American reported on June 18, 1881: “Had [Dolbear] been observant of patent office formalities, it is possible that the speaking telephone, now so widely credited to Mr. Bell would be garnered among his own laurels.”
Defeated but still energetic, Dolbear turned to wireless communications, and in 1882, while a professor at Tufts, he succeeded in sending signals a quarter mile using radio-wave transmission through the earth. Made wise by his bouts with Bell, he filed for and received a patent for his “wireless telegraph,” improving its transmission capability to a half mile by 1886. This was groundbreaking and beat out the theoretical work of German physicist Heinrich Hertz and, by a full decade, the practical inventions of the Italian Guglielmo Marconi. Dolbear’s patent later prevented Marconi’s company from doing business in the United States and forced the Italian to purchase Dolbear’s patent.
Dolbear even invented a system of incandescent lighting ahead of Thomas Edison, but here, reverting to earlier form, he didn’t pursue it fast enough to edge out Edison’s later monopoly. In short, he was an eyeblink from going down in history as the inventor of all the most important technologies of our time.
It seems that none of these inventors actually stole from the other. Rather, in a strange echo of nature’s predilection for patterns, the same ideas occured to different people at around the same time—a sort of hundredth monkey effect that seems to happen more often than random chance would suggest.3
Out of left field, and bearing no relation to applied physics, Amos Dolbear suddenly submitted an article that was accepted for publication in the November 1897 edition of The American Naturalist. Titled “The Cricket as a Thermometer,” Dolbear’s article spelled out the connection between the night’s temperature and the rate at which crickets chirp. The formula he expressed became known as Dolbear’s law, which still remains widely known in esoteric entomology circles. You simply count the number of chirps that occur in fourteen seconds and add forty. Voilà: You get the current temperature in degrees Fahrenheit. This assumes you’re hearing the snowy tree cricket, the most common variety in the United States.
Fame has fully eluded Amos Dolbear a century after he left this planet. Perhaps we can remedy this, just a little, by announcing the temperature during our next camping trip while grandly invoking Dolbear’s law.
Crickets easily catch our notice because we humans are very aware of repetitions that are roughly in sync with our own heartbeats—and crickets’ stridulation rate rarely diverges by more than 50 percent from this. We especially notice things that repeat between 0.5 and ten times a second. Slower than that and we may regard the individual events—such as the hooting of some owls—as independent and not link them into a single activity. Faster than that and we perceive them as a steady sound, its own sole event rather than an assembly of others.
For example, many mosquitoes give off an annoying drone in the musical note A, the same as a telephone’s dial tone.4
It’s caused by wings flapping at 440 beats per second. But other mosquitoes flap six hundred times a second, producing something like a D or D-sharp. In either case our ears perceive no sensation of separate mosquito beats. Anything more than about fifteen beats a second seems a single tone.
Meanwhile, as bees jerkily dart through the air to pollinate trees and flowers, their low, buzzing pitch comes from wings flapping 230 times a second, the note of A-sharp one full octave below the mosquito drone. But frogs and salamanders are ready for a variety of flying insects, as they quickly arise from their hibernation and start to fill the air with mating songs.
Above all the marshy melodramas, fireflies blink on and off. Their bioluminescence, caused by the enzyme luciferin interacting with oxygen, typically emits a yellow-green light in the same color as an aurora.5 And, like the northern lights, fireflies produce radiance without heat. Also like an aurora, fireflies produce light that is unreliable. The insects are only active for a few weeks in late spring and summer, only when the night is warmer than fifty degrees, and—for reasons that remain mysterious—they almost never turn on their lights west of Kansas.
As spring progresses, the season’s new crop of young mammals becomes obvious to country dwellers. We see bear cubs and fawns staying close to their mothers, but rarely do we observe the more secluded, furtive animals, such as coyotes, who have their pups then, too. None of these large mammals actually breeds in the spring. They mate during the previous fall, instinctively planning for their young to be born during spring’s food festival. Mostly it’s the small mammals who are going out on dates during the spring, and even they time their activities to catch the peak of the season’s abundance. Chipmunks start to be active enough to breed as early as February and are thus among the first mammals we see, even when patches of snow still prevail. They rely on having multiple entrances to their dens to evade predators, and they protect themselves with their jerky speed.
It’s often not enough. Despite some silly claims on the Web that various rodents can whiz along at thirty-five miles per hour, actual laboratory track tests and field measurements show that rodents have a top speed of about ten miles per hour, give or take a couple. They may seem much faster because, once again, they traverse many rodent lengths per second. But a mouse can only dash at eight miles per hour. The common eastern gray squirrel can hit twelve miles per hour on a good day. Unfortunately for them, they cannot outrace their usual predators if the match is held at a straightaway. A house cat can run more than three times faster than any mouse. It’s not a fair contest between Tom and Jerry.
WHO CAN CATCH WHOM
The Chase Is On: Top Speeds of Common Mammals
In Miles per Hour
Chipmunk 7
Mouse 8
Squirrel 12
White-tailed deer 30
Cat 30
Grizzly bear, black bear 30
Rabbit 30
Fox 42
Coyote 43
Fastest dogs 44
The very fastest animals? None races through American forests: it’s a tie between the cheetah and the sailfish. Both can reach sixty-eight miles per hour. The fastest-ever racehorse, at least in the 1.25-mile category, was Secretariat. That day in 1973 when he left all other horses in the distant dust while winning the Kentucky Derby, he posted an average speed of thirty-eight miles per hour.
As for winged animals, their speed depends on their motives. Most cruise at twenty to thirty miles per hour, and this is true for small birds as well as large ones. Geese and hummingbirds fly at the same speed. Nearly all birds can tuck in their wings and dive much faster than they can fly should the need arise. Peregrine falcons are renowned as the very swiftest birds, able to achieve two hundred miles per hour in a dive, although half that is their usual behavior. However, even two hundred miles per hour is perhaps no “achievement”: a hu
man skydiver reaches that same speed in a headfirst posture with his arms tucked to his sides. It’s the simple matter of terminal velocity; no skill required. A falcon cannot outrace a diving daredevil.
Nearly all birds fly between twenty and thirty miles per hour. But their wing-beat rates vary enormously: it’s 1,250 flaps per minute in hummingbirds but closer to one hundred flaps per minute in these greylag geese. (Michael Maggs, Wikimedia Commons)
Birds can catch field mice, squirrels, and chipmunks without batting an eye. Squirrels have the most visibly dramatic strategy of defense, routinely zigzagging so that a swooping hawk has a hard time aiming at the fleeing rodent. But birds can and do choose different speeds for different purposes. A hawk on reconnaissance patrol, loitering in the sky in search of prey, would want to maximize her endurance and move her wings leisurely to preserve energy and stay aloft for hours. But a seabird trying to reach a distant hunting ground would want to maximize her range. This doesn’t usually entail going fast or even flying long distances through the air; exploiting wind currents might be the key. And birds are sometimes forced to maximize speed, as they do when pursued by a predator.
Suffice it to say that nearly all birds fly between ten and forty miles per hour, and most cruise in the twenty-to-thirty range. Plenty fast enough to catch flying insects, few of which can attain twenty miles per hour.
But more is happening than meets the eye. What we see is, in many ways, not as fascinating as what we could potentially detect with X-ray vision (with which we could peer through bark) or time-lapse perception, because the most dramatic magic unfolding in spring is the act of growth.
Trees are classified according to a slow, medium, or fast growing rate. Slow means less than a foot a year. Fast means more than two feet. Medium is in between. Each species is distinct. Sugar maples barely alter their appearance year over year, while willows change shape quickly.
HOW FAST DO TREES GROW?
Fast (≥2 feet / yr) Medium Slow (≤1 foot / yr)
Elm Linden Balsam fir
Honey locust Norway maple Black walnut
Red maple Scotch pine White oak
Ash Red pine Butternut
Birch Spruce Sugar maple
Black locust White pine
Box elder
Cottonwood
Red oak
Silver maple
Willow
Spring brings the year’s fastest growth in trees and plants alike; shoots push up as much as an inch a day. None of it crosses the threshold of visible motion. The plants that come closest are some of the climbing ivies, which use almost spooky holdfasts, and the wraparound climbing stems of wisteria, which can extend ten feet per season and which seem science fiction–like when viewed through time-lapse photography.
Likewise, if we could peer through the ground, we would see snaking roots advancing by two inches to as much as two feet per week. The all-time growth winner, however, is not a plant most of us get to enjoy. It’s bamboo. This can emerge from the earth at its full thickness and then head upward at speeds just barely too slow to visually discern. The all-time record is a measured thirty-nine inches in a single day. That’s one and a half inches an hour.
So this single season, spring, reliably delivers nature’s outstanding hurry-up exhibits. Quick change is what’s dramatic, especially when clothed in vivid colors—and change is another word for motion.
PART II
THE PACE QUICKENS
CHAPTER 8: The Gang That Deciphered the Wind
A Desert Dweller’s Airy Spells Last for a Millennium, While Two Oddballs Dodge the Inquisition
Gray-eyed Athena sent them a favorable breeze,
A fresh west wind, singing over the wine-dark sea.
—HOMER, THE ODYSSEY (CA. EIGHTH CENTURY BCE)
In the Bible, John 3:8 says, “The wind bloweth… and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth.”
Blowing wind had started me on this quest to understand natural motion. Yet being harmed by the wind was hardly a unique experience. It’s a familiar scenario in global literature. The specter of an invisible entity that destroys houses has aroused fear through the ages.
But I knew where I must goeth. To the consistently windiest place in the hemisphere. Where anemometers measured the all-time fastest-ever wind gust in a record that stood for more than a half century. That blast duplicated the inside of an EF4 tornado.1
New Hampshire’s Mount Washington stands for more than mere Guinness-type record holding. Its famous gusts make people itch to experience the wind for themselves. To accommodate them, the state built a road to the summit back when Abraham Lincoln was in the White House. Families looking for a bit of adventure authenticated by a boastful bumper sticker have made the pilgrimage ever since.
Sure, I could lazily get in my old four-seater plane and fly myself over that 6,288-foot peak, but how would that bestow the experience of its famous winds? Besides, I was scared. Wind acts in violent ways around mountains, and Mount Washington possesses an odd configuration that funnels the air with the best of them. I remember reading about a Boeing 707 jetliner flying near Mount Fuji in Japan on March 5, 1966, that, tragically, had its tail torn off by orologically induced turbulence.2
Who in ancient times could have begun to understand swirly air? Who could visualize any mechanism by which Earth’s five thousand trillion tons of gas are set into perennial motion? None of the ancients tackled the whats, hows, or whys of the gaseous realm. The Westerner who went the furthest was Aristotle, who declared air to be an “element” that liked to rise.
Instead, people asked how moving air could benefit them: What’s in it for me? One of the first technological lightbulbs to go boing in the ancients’ minds was the idea of employing air as a free power source.
Air energy has been harnessed since earliest recorded history, even by a sparse human population that didn’t reach two hundred million until the time of Christ. As far back as 5000 BCE, wind propelled boats along the Nile. By biblical times, sailboats were a common sight.
It took an amazingly long time—fully five thousand years after the first canvas sails—before moving air was utilized mechanically. The Chinese did it first, around 200 BCE, when they erected windmills and fitted them with gears that pumped water for irrigation. Soon after, the idea spread to the Middle East, where inhabitants built windmills that had woven reed sails and were geared with a vertical revolving shaft for grinding grain.
The Persians were next in line to use wind power and introduced it to the European regions still under the rule of the Roman Empire by 250 CE. Another few centuries of achingly slow technological progress brought an upgrade to Windmills 2.1, which featured better materials, such as metal gears, and larger, more efficient vanes. These windmills appeared in Afghanistan in the seventh century and Holland by the 1200s. These bigger structures grandly drained marshes and fertilized fields and ultimately even pumped water for American settlers heading west in the 1800s.
For all that, no one seemed obsessed with figuring out what, exactly, is air. Or how far it extended upward, or why it should ever budge. No one guessed that it’s a blend of different gases, each with distinct properties. No one puzzled over the bizarre fact that—unlike the sun and moon and the habitual tides and the seasonal rains and the predictable cycles of crops and insects and such—the wind acted capriciously. Sometimes it didn’t waft at all, then it could howl destructively an hour later. Strong winds often accompanied thunderstorms. Yet equally ferocious winds could blow from cloudless skies. No other aspect of the everyday environment displayed such wild whimsy.
Even in the early twentieth century, no one knew about well-defined air masses. It wasn’t until after World War I, appropriately enough, that the word front was coined to describe this novel idea of warring globs of air that produce inclement weather along their boundaries.
The really juicy discoveries started in the eighteenth century and then accelerated in the n
ineteenth. But a few brilliant thinkers made laudable contributions much earlier.
It was Aristotle in 350 BCE who coined the word meteorology, which is simply Greek for the science of “high in the sky.” But the study of the atmosphere and its rich, vast, and varied antics perhaps began in earnest a half millennium earlier in India, when the ancient holy texts of the Upanishads were composed. These writings discuss at length the ways in which clouds form and rain is produced and even attribute the phenomenon to the seasonal cycles that result from the movement of Earth around the sun.3 Around the year 500 CE, Varāhamihira wrote the classical Sanskrit work Brihat Samhita, which expounds on complex atmospheric processes such as hydrolic cycles, cloud formation, and temperature transformations attributable to solar heating.
Another half millennium passed with the Western world sound asleep. It was the Dark Ages, when advancements—so promising during the glory days of the Greeks and in ancient India and China—simply stopped cold until the 1500s. Or so we are taught. What everyone forgets are the four wonderful centuries when knowledge was prized in Persia and the Middle East. This was the golden age of Arabic science. While one side was dark, another basked in the sun.
I have a hero from this era. Born in Basra in what is now Iraq in 965 CE, he was Abu Ali al-Hasan ibn al-Hasan ibn al-Haytham, familiarly called ibn-al Haytham in the Arab world. Let’s be gentle on ourselves and refer to him by his Latinized name—Alhazen.
He had extensive knowledge of the Greeks and wrote approvingly of Aristotle and disapprovingly of Ptolemy. In what was a groundbreaking approach, he did not merely theorize or speculate but performed careful experiments.