How One Farmer’s Curiosity Revealed the Hidden Beauty of Snow Crystals and Pioneered Meteorology
From The Observatory
Source: Public Domain Review
Wilson Bentley, a self-taught farmer in Vermont, captured thousands of snowflakes on film, revealing their intricate designs and leaving a lasting legacy in meteorology and the study of nature’s frozen wonders.
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In 1885, at the age of 20, Wilson Alwyn Bentley, a farmer who would live all his life in the small town of Jericho in Vermont, gave the world its first ever photograph of a snowflake. Over the following winters until he died in 1931, Bentley captured over 5,000 snowflakes, or more accurately, snow crystals, on film. Although he rarely left Jericho, thousands of Americans knew him as “The Snowflake Man” or simply “Snowflake Bentley.” Our belief that “no two snowflakes are alike” stems from a line in a 1925 report in which he remarked: “Every crystal was a masterpiece of design, and no one design was ever repeated. When a snowflake melted, that design was forever lost.”
It started with a microscope his mother gave him when he was 15. A lover of winter, he made plans to use his microscope to view snowflakes. His initial investigations proved both fascinating and frustrating as he tried to observe the short-lived flakes. So that he could share his discoveries, he began by sketching what he saw, accumulating several hundred sketches by his 17th birthday. When his father purchased a camera for him, Bentley combined it with his microscope and, on January 15, 1885, made his first successful photomicrograph of a snow crystal.
In addition to developing the hardware, Bentley also had to devise a protocol to capture a snow crystal and transport it without damaging the camera’s field of view. What he found worked best was capturing the crystals on a cool velvet-covered tray. Taking care not to melt the crystal with his breath, he identified a suitable subject and lifted it onto a pre-cooled slide with a thin wood splint from his mother’s broom and nudged it into place with a turkey feather. The slide was then carried into his photographic shed and placed under the microscope. The back-lit image was focused using a system of strings and pulleys he devised to accommodate his mittened hands. Once focused, the sensitized glass plate—or “film”—was exposed and stored for further processing, development, and printing.
Bentley also devised his own processing methods. In addition to developing the original image, he also created a post-development process to enhance it. Since each photograph was taken of a white snow crystal against a white background, Bentley was dissatisfied with the initial photograph. He felt he could improve the contrast and enhance the detail by presenting the crystal against a dark background. To do this, he painstakingly scraped away the dark emulsion surrounding the snow crystal image from a duplicate of the original negative using a sharp penknife and steady hand. The altered image was then carefully placed on a clear glass plate and printed, giving it a dark background. Even after years of practice, this post-production process often took as long as four hours for a complex snow crystal.
With 70 to 75 photographs per storm and notes on the conditions under which they were collected, Bentley accrued a considerable understanding of snow. In 1897, he met Professor George Perkins, a geologist at the University of Vermont. Together, they prepared the first paper on snow crystals, published in the May 1898 issue of Appleton’s Popular Science Monthly, entitled “A Study of Snow Crystals.”
While photographing snowflakes was his passion, Bentley also turned his interest to examining and sizing raindrops for seven summers from 1898 to 1904. From that work, he gave us early insights into raindrops and their size distribution in storms. After some experimentation, he developed a simple yet effective apparatus for gathering raindrops: a shallow pan of wheat flour. At first, he simply photographed the rain imprints on the flour. Then in 1898, he made a serendipitous finding. In his journal, he wrote: “In the bottom of each raindrop impression in the flour, there could always be found a roundish granule of dough nearly the exact size of a raindrop. After experimenting with artificial raindrops, I could measure [their] diameter before falling into the flour, and thus tell if the dough granule corresponded in size with the measured raindrop.”
Bentley measured these raindrop “fossils” and divided them into one of five size-range categories. Over the course of his raindrop studies, he collected 344 sets of raindrop pellets from over 70 distinct storms, including 25 thunderstorms. He added meticulous weather data for each storm: date, time of day, temperature, wind, cloud type, and estimated cloud height. He concluded that different storms produce raindrops of various sizes and different size distributions. Few rainfall events had uniform drop sizes, but when they did, he discovered they were composed of either all small drops or all large drops. Low rain clouds produced mostly small drops. The most significant drops, around a quarter of an inch in diameter, fell from the tall cumulonimbus clouds of thunderstorms. He concluded that the sizes of drops and snowflakes could reveal a great deal about the storm’s vertical structure.
Unfortunately, Bentley was so far ahead of his time that contemporary scientists didn’t fully appreciate him. They didn’t take the self-educated farmer seriously. His raindrop work was only rediscovered and corroborated 40 years later in the 1940s, when the study of cloud physics and precipitation processes began to blossom. It appears that the first to recognize Bentley’s raindrop experiments were scientists J.O. Laws and D.A. Parsons from the U.S. Soil Conservation Service (now called the Natural Resources Conservation Service), who published a paper in 1943 reporting measurements of raindrop size under various rainfall intensities using Bentley’s collection method.
Although he quit studying raindrops after a few years, he continued to photograph snow crystals and to speculate on the nature of snow. From his extensive data archive, Bentley’s analysis convinced him that the form the ice crystal took—hexagonal plate, six-sided star, hexagonal column, needle, etc.—was dependent on the air temperature in which the crystal formed and fell. Nearly three decades would pass before Japanese physicist and science essayist Ukichiro Nakaya would confirm this hypothesis.
Bentley also sought to promote his work for its beauty, submitting articles and delivering lectures that focused on his snow photography over the years. His lectures were popular, and because of them, he was dubbed The Snowflake Man and Snowflake Bentley by the newspapers. More than 100 articles were published in well-known newspapers and magazines, including the Christian Herald, Popular Mechanics, National Geographic, the New York Times Magazine, and the American Annual of Photography. His best photographs were in demand from jewelers, engravers, and textile makers who saw the beauty in his work.
He also submitted technical reports to the U.S. Weather Bureau’s (now the National Weather Service) publication Monthly Weather Review. Although he received scant recognition from most scientists, he did receive encouragement from Weather Bureau chief meteorologist William J. Humphreys, who helped him publish a collection of his photographs. Humphreys wrote the technical introduction and appeared as a co-author. The book Snow Crystals by Bentley and Humphreys was published by McGraw-Hill in November 1931. It contained 2,500 selected snow crystal photos plus 100 photos of frost and dew formation. Dover Books has since republished the book.
As a grown man, Bentley was slight of frame, likely just over five feet tall and weighing around 120 pounds, but he could dig a row of potatoes or pitch hay as well as any farmer in the valley. He continued to farm the acreage with his older brother for the rest of his life. Though not an outgoing man, he loved to entertain by playing the piano or violin and singing popular songs. He also played clarinet in a small brass band and could imitate the sounds of many animals. Bentley never married.
In early December 1931, Bentley walked six miles, ill-dressed, through a slushy snowstorm to reach his home. Not long thereafter, he contracted a cold, which turned into pneumonia. “Snowflake” Bentley died on December 23 at the age of 66. In March of that year, he had taken the last of his photomicrographs of snow, still using the same camera that had taken the first.
Although his father thought his snow photography was nonsense and not proper for a farmer, Bentley broke new ground in the early days of modern meteorology and microscopic photography. His biographer, cloud physicist Duncan Blanchard, dubbed him “America’s First Cloud Physicist.” The Burlington Free Press wrote in a Christmas Eve obituary for Bentley:
Longfellow said that genius is infinite painstaking. John Ruskin declared that genius is only a superior power of seeing. Wilson Bentley was a living example of this type of genius. He saw something in the snowflakes which other men failed to see, not because they could not see, but because they had not the patience and the understanding to look.
On the morning he was laid to rest in the Jericho Center cemetery, it began to snow, leaving a dusting over the burial ground.
