How amateur telescope makers helped defend America

01 May 2024
By Jeff Hecht
James Baker’s 1941 optical shop in the Harvard College Observatory’s basement. Photo credit: John G. Wolbach Library/National Archives in Boston

John Mellish, a young Wisconsin farmer with a grade-school education, wanted to see the stars. But at the turn of the 20th Century, a three-inch refractor from optics manufacturer Alvan Clark & Sons cost $175, a sum far out of reach for Mellish. But he was handy. An article on telescope making by astronomer George Ritchey in Scientific American taught him enough to build, for just $15, a six-inch Newtonian telescope, which he would later use to discover two comets. After Popular Mechanics published his letter to the editor telling how he did it, Mellish received more than 300 letters in reply, which launched an unexpected career making and selling telescopes.

It was Mellish’s work that inspired the gifted, energetic, and restless Russell Porter, who launched the enduring hobby of amateur telescope making in the US. Born in Springfield, Vermont in 1871, Porter studied art, engineering, and architecture before joining eight Arctic expeditions, from 1893 to 1906, that left him worn out. While he was recovering, a friend gave Porter a pile of issues of Popular Mechanics, where he encountered Mellish’s popular letter to the editor and became interested in optics and astronomy.

By 1912, Porter was making good telescope mirrors, and by 1920, he had perfected his skills enough to teach telescope-making to 16 people, most from a local machine shop. They included the only woman working at the shop, Gladys M. Piper, a drafter. This group, minus Piper, who moved away in 1921, would form the nucleus of the nation’s first amateur telescope club, the Springfield Telescope Makers—a group that still thrives and hosts an annual star party known as the Stellafane convention. In 1921, Porter wrote “The Poor Man’s Telescope,” an article published in the November 1921 issue of Popular Astronomy.

Porter saw in the 1920s that the time was ripe for amateur telescope making. Optical glass was in good supply, equipment was available, and many people knew how to use machines. Yet, his article got little attention. That “might have been the end of the story for Porter had it not been for the entrance of another remarkable character in the saga, Albert Graham Ingalls,” writes Thomas R. Williams, a historian and amateur astronomer, in his 2000 doctoral dissertation at Rice University on the history of amateur astronomy in the US.

Scientific American had hired Ingalls in 1923 to write about how-to projects that would involve readers. When he found “The Poor Man’s Telescope” in the New York Public Library, Ingalls knew it had possibilities. He contacted Porter, the two corresponded and visited each other, and Porter helped Ingalls make his own telescope.

Ingalls made telescope-making seem easy in the November 1925 issue of Scientific American. “You must be handy, of course, but you do not have to be a genius. Patience is necessary, but no knowledge of mathematics, abstruse science, or astronomy itself is required,” he wrote. All you needed was a barrel to work on, two glass disks, pitch, optical rouge, abrasives, household tools, and the patience to push one disc over the other to grind the glass.

Readers asked for more, and a three-part series followed in early 1926. A longer book version came after that, selling for $2 postpaid, which went through three more editions and remained widely used for decades. At the end of 1926, Ingalls counted more than 1,500 readers who were building telescopes.

Amateur astronomy and telescope clubs spread across the country: New York City, Chicago, Denver, and Los Angeles. By May 1928, the number of telescope makers had doubled, and readers were actively sharing their ideas in Ingalls’ column rather than just reading instructions. His column became the backbone of the newly formed community of amateur telescope makers. 

The Great Depression began in 1929, and it hit big optics companies hard. Yet amateur telescope making grew. It was a good project for the many people with plenty of time on their hands but very little money. Ingalls “kept up a relentless drum beat for amateur telescope making in his Scientific American column,” writes Williams. The environment was helpful and welcoming. “Anyone with a few simple tools could construct a high-quality astronomical telescope for a relatively trifling cost,” historian Gary Leonard Cameron noted in his 2010 doctoral dissertation.


James Baker’s 1942 optical shop, originally intended to hold the New England Depository Library, but commandeered for war work. Photo credit: John G. Wolbach Library/National Archives in Boston

Meanwhile, tensions were rising in Europe. “In retrospect, 1936 marked the military prelude to world conflict,” wrote aerial photography pioneer Gen. George Goddard in his memoirs. The US had spent heavily on optics during World War I to catch up with German technology, but investment in military materiel slumped after that war ended. In the decades following, Germany seemed ahead in precision optics for surveillance, cameras, and gunsights. Moreover, the optics industry worried they lacked the production capacity they would need if another war broke out.

A top concern was the high-quality image inverters needed for surveillance binoculars and optics for aiming weapons. The best available image inverters were Amici roof prisms, in which the roofs were internal reflection surfaces inside the prisms with very low loss. “The design is very complicated; instead of the five sides of a regular 60-degree or 90-degree prism, a roof prism has nine sides, all of which must be very accurately aligned with one another,” says Cameron. The task was so difficult, Williams writes, “there were fewer than two dozen optical workers in the United States who could manufacture a passable Amici roof prism.”

Ingalls learned of the problem in 1937 and discussed it with his brain trust of amateur “telescope nuts.” He asked one of the best telescope makers, Fred B. Ferson of Biloxi, Mississippi, to learn how to fabricate roof prisms. By 1940, when Bausch & Lomb warned of a serious shortage of technicians able to produce military optics, the diligent Ferson was already making roof prisms in his garage for Spencer Optics. 

Ferson’s feat showed that telescope makers could produce complex optics, but with war nearing, more help was needed. In September 1941, three months before Pearl Harbor, Porter—who had since relocated to California to work on the Palomar telescope—began recruiting members of the Los Angeles Astronomical Society and the Milwaukee Astronomical Society. Ingalls, Ferson, and Porter dubbed the volunteers “the roof prism gang.”

And yet, the volunteer team lacked a standard manufacturing procedure. Ingalls, Ferson, and Porter teamed with Herschel Ice, an amateur telescope maker then working at the US Army Frankford Arsenal, to write one. Porter, an accomplished artist and architect, contributed illustrations. Instructions were mimeographed and mailed to the 23 volunteers thought most able to do the work. Each volunteer made two sample prisms and sent them to the Frankford Arsenal in Philadelphia for examination. Those whose work passed went on to produce larger batches of 25 or 50 prisms for further testing.

In the end, 80 amateurs joined the Roof Prism Gang, with Ingalls coordinating the project and cheering them on.

The program met military needs. Williams wrote, “The Roof Prism Gang manufactured about 10 percent of the total military demand. The production of acceptable prisms by individual members of the gang ranged from a few dozen to the 11,600 turned out by Fred Ferson. The total production of the Roof Prism Gang amounted to 28,420 prisms.” After early problems were solved, the yield exceeded 90 percent, which Frankford officials said even major companies with professional opticians did not exceed.

Throughout the war effort, amateur astronomers pitched in to teach soldiers, sailors, and aviators how to identify stars, use spherical trigonometry, and do celestial navigation. The Army Air Corps sought amateurs 20- to 27-years-old to enlist and become air navigators. The Army sought experienced observers to join the civilian Aircraft Warning Service and watch the skies for enemy bombers.

The military also brought astronomers directly into war work on optics. Once Goddard realized war was inevitable, he pushed for the development of wider-aperture cameras for longer-range airborne reconnaissance. James G. Baker, a young Harvard astronomer, was recommended to him as a budding genius in optical design who loved astronomy but was “poor as a church mouse.”

Baker had made telescopes in his teens and, after he moved to Harvard, began helping the Amateur Telescope Makers of Boston to build a 20-inch diameter Cassegrain telescope. The group of 23 who founded the club in 1927 had included Thelma Johnson, who was taking a course at Harvard and became the first woman in Boston to make a telescope. A reporter for the Boston Herald who visited the club reported in 1934, “the women in the club are more enthusiastic than the men, if that is possible."

Goddard met Baker in 1941 in the club’s cluttered workshop in the Harvard College Observatory attic. When Goddard said he wanted to push the envelope in long-range photoreconnaissance by making lenses able to correct for altitude, he wrote, Baker “didn’t bat an eye.” However, the professor did hesitate when Goddard asked how he would design an advanced 40-inch focal length reconnaissance camera. Goddard baited the hook, asking “Do you think $25,000 would cover the cost?” The astronomer’s jaw dropped. Accustomed to the frugal world of astronomy, Baker repeated the number to make sure he had not misunderstood. Then he said, “Why for that amount I can develop practically anything.”

Goddard invited Baker to visit Wright Field in Dayton to discuss potential issues with top Army Air Corps engineers and physicists. After Baker produced two new designs for 40-inch focal length lenses that impressed Goddard, he got money to set up an optics lab at Harvard to make and test large lenses.

Although most members of the Boston telescope club stopped coming to club meetings to devote their time to nonoptical war duties, a few came to Harvard for weekly tutorials and joined Baker in developing bigger and better reconnaissance lenses in the Harvard optics lab. In 1942, the optics project outgrew the attic and moved into a larger shop in the observatory basement.

In 1943, the Army Air Corps expanded big-lens development at Harvard, naming it the “Observatory Optical Project” (inevitably dubbed OOP), and classifying the project. The goals were to scale wide-angle lenses from focal lengths of 40 inches to 60 and 100 inches, and to test them in the air at low pressure.

First tests of a new distortionless 60-inch f/6.0 telephoto lens with automatic focusing adjusted by changing air pressure got a glowing report from Goddard: “On its first test, large-scale pictures from 30,000 feet showed remarkable detail.” It was the breakthrough he had been hoping for, and the 60-inch camera immediately went into operation over enemy territory. The Harvard lab produced about 100 such cameras, which flew on Lockheed P-38 Lightning and the Boeing-29 Superfortress aircraft during the war and afterwards.

The next step for Baker’s group was to start developing cameras with focal lengths of 100- and 240-inches. In early 1945, they moved out of the basement and into a custom-designed building.

Despite the OOP’s achievements, the end of the war brought the end of the project. The Harvard administration chose to abandon military research after the war ended, so they shut the lab and tore down the brand-new building. In 1946, the equipment and many of the male former members of the OOP staff moved to Boston University, which continued developing aerial reconnaissance optics with military support.

“Women became much more involved in astronomy following WWII,” Cameron wrote in 2010. That may have held for amateur astronomers and teachers, but it did not hold in the optics industry. Even before the war ended, political pressure had built to put veterans back to work when they came home, and that meant pushing women out of many traditionally male industrial jobs.

James Baker, George Goddard, Albert Ingalls, Russell Porter, and John Mellish make up only a portion of the cast of characters involved in the launch of amateur telescope building. Their knowledge, collaboration, and passion for telescopes throughout the past century ultimately contributed to advanced optical systems during WWII and the Cold War. That’s quite a legacy for a Wisconsin farmer who just wanted to get a closer look at the stars.

Jeff Hecht is an SPIE Member and freelancer who writes about science and technology.


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