Counting Stars

Counting Stars Blog BannerWelcome to the musings and maunderings of the staff of Dudley Observatory at the Museum of Science and Innovation.

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Dr. Boss and the Martians

By now, you’ve probably seen our Outreach Astronomer, Dr. Rapson, talking about the new discovery of exoplanets around the TRAPPIST-1 system.  Or maybe you’ve heard her talking about the coming solar eclipse, or the discovery of water on Mars, or any of a number of astronomical topics.  She’s fulfilling a role that the representatives from Dudley have played for over a century: explaining new developments in astronomy to the public of the Capital region.

Of our directors, Dr. Benjamin Boss was the most active public scientist.  Local papers frequently went to his to deliver an explanation or a verdict.  And it wasn’t always restricted to astronomy; when an earthquake shook Albany in October, 1935, Dr. Boss could be found in the Albany Times-Union explaining fault lines.

And sometimes, he could be found crushing a dream …

Albany Times-Union, November 12, 1931

The gist of the article is that a group of scientists were speculating on a rocket trip to Mars.  The TU turned to “internationally noted authority on astronomy” Benjamin Boss.  Boss explained some of the difficulties: the duration of the trip and the need for supplies and oxygen, the damage that could be inflicted by the velocities at take off and the velocity on hitting Mars, and the fact that there would be no obvious way back.

Apparently the editors of the TU decided to run through their clippings file on Mars and include whatever pictures they found. The “martian” is Oamaruru, the martian woman who was supposedly in psychic contact with Dr. Hugh Mansfield Robinson in the 1920s.  That raises questions about who these scientists planning a trip to Mars actually are.

(“But all these dreams are shattered by Dr. Benjamin Boss, noted astrologist …”  I dare you to call Dr. Rapson an “astrologist.”  Just wait until I’m in another room.)

From the Collection: Velocity Model

Image collections can be an entertaining headache.  Imagine someone going through the shoebox of old photographs that your parents keep in the closet and trying to figure out each picture.  Sometimes the subject of the photo will be obvious. Other times it will be something that no one will ever be able to puzzle out without having been there.

Dudley has a modest collection* of glass plate negatives from the time of Benjamin Boss.  They seem to be part of Boss’s personal collection, so the shots of galaxies and lunar eclipses are mixed in with his wedding photographs and pictures of his children.  And there are also several pictures of whatever this thing is:

Galactic Velocity Model

The images were only labeled  “velocity model,” which isn’t very helpful.  It took a lot of digging, but eventually I stumbled across this bit from an interview with Boss:

Aided by an ordinary box which he had constructed, Dr. Boss was able to demonstrate the startling bit of news that the Milky Way actually spins or rotates.

Dr. Boss had ingenuously stretched fine lengths of thread between the top and bottom side of the box and upon which were fixed small beads. Dr. Boss pointed out that each small bead attached to the thread represented a star in the Milky Way. The entire cluster of beads suggested that they had been scattered, as a farmer scatters seed within the 180 degree angle. Dr. Boss then said that, were it possible to bring all the stars in the Milky Way into a small cluster to be held or fixed and then released for one minute and then fixed again, the stars in the Milky Way would appear in relatively the small positions he had arranged the beads. This, Dr. Boss said, proves to his satisfaction that Milky Way with its more than 30 billion stars is in reality a spinning or rotating mass.

– Albany Times-Union, Nov 24, 1935, p.2-B

Dudley’s major function during early twentieth century was creating a catalog of star positions and velocities.  This kind of work can be dismissed as boring “stamp collecting,” but it lead to some major scientific discoveries.  Here Benjamin Boss was using a simple model to show the three-dimensional position of stars within our galaxy to show how their motion leads to the realization that the whole galaxy is rotating.


(*) Bear in mind that I’m sitting next to miSci’s collection of GE photographs.  With 1.6 million photographs and negatives, it’s one of the largest image collections in the world.  In this building, anything that doesn’t fill a room will be considered “modest.”

The Total Eclipse of 1878

Harper's Weekly, July 1878 Eclipse

Harper’s Weekly, July 1878 Eclipse

As we gear up for the Eclipse Across America this summer, it’s worth looking back at the history of eclipse viewing and the role it played in modern astronomy.  Treks out to some remote location to view a solar eclipse were a type of pilgrimage for American astronomers, bringing together large numbers of scientists in one remote location.  Questions were answered, rivalries were struck, scores were settled and a lot of good science was accomplished.

One of the most interesting was the solar eclipse of July 1878, which allowed several old friends (and enemies) to settle one of the most vexing questions of 19th century astronomy.

The path of the 1878 eclipse made it visible from Alaska down through the Rockies and then into the Gulf of Mexico and Cuba.  There were a number of sites in its path that would be ideal for viewing: dry, elevated and dark.  Even better: the decade old transcontinental railroad ran out to the path of the eclipse, meaning that astronomers could take along all the bulky equipment they could ship.

So the scientific community boxed up their gear and headed out to Rawlins, Wyoming, where the total eclipse would be visible for two minutes, fifty-six seconds.  Along for the trip were men like Simon Newcomb of the Naval Observatory, soon to become possibly the most famous astronomer in America.  Also in attendance was Norman Lockyer, founder of the journal Nature, and James Craig Watson of the Ann Arbor Observatory.

And also a 31 year old tinkerer named Thomas Edison, but that’s another story.

The eclipse viewing crew, led by Henry Draper.

The eclipse viewing crew, led by Henry Draper.  Edison is second from the right.  The two women are Mrs. Draper and Mrs. Watson.  It’s nearly impossible to identify the rest of the mustached mass of men.

There was a great deal of scientific work to be done in the just-under three minutes of the eclipse, but the goal that caught the popular attention was the search for the hypothetical planet Vulcan.  

The French mathematician Urbain Le Verrier had theorized the existence of this small planet in between Mercury and the Sun during the mid 19th century.  Many astronomers considered it the most likely explanation for certain irregularities in the orbit of Mercury.  But finding it had proved difficult. Many astronomers had caught fleeting glimpses of something in the right vicinity – asteroid, sunspot or maybe a small planet.

The search for Vulcan had taken on a new urgency after an eclipse in 1869, thanks to our own Benjamin Gould.  After leaving Dudley, Gould had become one of the early astronomers skilled in photo-astronomy.  He set up his equipment in Burlington, Iowa, during the eclipse in order to photograph the solar corona.  On the right bank of the Mississippi he snapped forty two images of the eclipse.

Gould reasoned that if there was a planet orbiting between Mercury and the Sun, then it should be visible in the shadow of the eclipse.  He examined his own photographs, plus over three hundred other photographs of the eclipse, and came to the conclusion that nothing was there.  Not a man for mincing words, Gould announced, “I am convinced that this investigation dispenses with the hypothesis that the movement of the perihelion of Mercury results from the effects of one or many small interior planets.”

For Gould, the matter was settled.  But popular theories don’t die that easily.  For a while, most astronomers continued to find nothing.  Then in April, 1876, a German astronomer working in northern China named Heinrich Weber sent a telegram back to Europe announcing that he had seen a circular object in transit across the Sun.  Once again, the game was afoot.

America was still struggling to catch up to Europe in the realm of science. Many in the American scientific community would have loved to find Vulcan from a spot on American soil.  So many of those tromping out to Wyoming were hoping to be the one to spot the rogue planet.  

In the end, the verdict was mixed.  Most of the astronomers, including Newcomb, had found nothing.  Watson had, and Watson was a well respected observer.  He also seemed to be supported by Lewis Swift, an amateur astronomer from Rochester who had been observing the eclipse in Denver.  

Rochester has produced many fine astronomers, but in the end it came down to what Watson believed he saw.  Surprisingly, Benjamin Gould’s verdict on Vulcan ended up being supported by his arch-nemesis – and fellow Dudley alumni – Christian F.H. Peters.  After leaving Dudley, Peters had ended up at Hamilton College are racked up an impressive number of asteroid discoveries.  He had been a Vulcan skeptic since the beginning, and he left no doubt that he believed Watson had made some basic errors in his supposed sighting.

While the journal Nature chided Peters for his tone, few seemed eager to defend Watson’s observations.  After the bulk of the astronomers viewing the 1878 eclipse reported no luck in spotting Vulcan, the pendulum seems to shift towards skepticism.  The problems with Mercury’s orbit remained, but the search for Vulcan drifted to a close.  In 1915, Albert Einstein was able to use his new theories of gravitation to accurately predict the orbit of Mercury, ending any need for another planet and closing the debate.

Goulds all the way back

There’s one advantage to inheriting a library; you don’t just get the books, you also get the bookmarks.  This bit of paper was found in one of the books used by Benjamin Gould.  On one side are some calculations.  On this side is a rough family tree.

Like any good Boston pure-blood, Gould was very interested in his own genealogy.  I know we’ve got some fans who can trace their lineage back to Gould’s family, so I thought this might be useful.

In the third column, the John Gould that is married to Sarah Parker would probably be Lieutenant John Gould (1635-1710), who served during King Phillip’s War.  Since he had eight children, you can see that this listing is very partial.

Benjamin A. Gould Family Tree (Gould Papers, B6,F6)

Benjamin A. Gould Family Tree (Gould Papers, B6,F6)

I’m afraid that all future generations will find in my books are the backs of Netflix envelopes and old receipts.  I feel like I’m failing history.


grand theodoliteIn regards to the last post, here’s Verplanck Colvin himself, taking notes on the right.  The instrument he’s using is called a theodolite, which is essentially a small rotating telescope for measuring horizontal and vertical angles.  Well, I guess in this case it’s not really a small telescope at all.  That looks like a brass telescope, maybe 4″ or so.

Colvin called this his “grand theodolite,” and last I checked, no one was sure where it had ended up.  Such a big and impressive big of technology porbably wasn’t scrapped (although, given that he and his crew had to hump this thing up and down a mountain, they probably wanted to).  If anybody has any idea, I’d love to know what happened to it.













barometerHere’s a less portable piece of technology.  This is George Washington Hough’s “automatic registering and printing barometer.”  It was Hough’s pride and joy.  He the bulk of the second Dudley annals describing it and showing tables of its results.

The object labeled B is a cylinder of mercury attached to a support frame that is bolted to a brick wall in the observatory.  A float is suspended in the mercury which rises and falls reacting to changes in the air pressure.  Changes in the position of the float trigger electromagnets, which release gears in the mechanism and cause the pen arm, S, to change position to match the float.  A drum wrapped in paper, O, rotates against the pen, recording a steady line that peaks and dips with the pen arm.

The weights at the bottom power the gears and the drum.  A battery powers the electromagnets.  By using batteries just to lock and unlock the gears, the use of electricity could be kept to a minimum.  Important in an are where recharging batteries required refreshing the chemicals.

Obviously it’s more complicated than I’m making it sound, but Hough was able to make it work.  It’s probably worth mentioning that when Hough was laid off in 1873, he went into private business selling his own inventions and was apparently successful.

How to Measure a Mountain Without Leaving Your Observatory

Nineteenth century observatories were more than just places to look at the stars.  They were packed with scientific instruments that were useful for all sorts of purposes: highly accurate clocks, barometers, thermometers, transits and other surveying equipment, and so on.  Many observatories were staffed by people eager to reach out to the public, either as part of their mission or to justify their funding.  Observatories could become little temples of science for their community.

As a rare privately funded observatory unattached to a university, Dudley had (and has) a strong need to be useful to the community which created it.  I’ve mentioned Benjamin Gould’s plan to provide accurate time for New York.  Since time is a measure of the earth’s rotation, the observatory could help mapmakers determine longitude. Dudley also offered public viewings to all, right through the Civil War.

Here’s one interesting example of Dudley making its scientific resources available.  In 1870, the naturalist and engineer Verplanck Colvin was working on a geological survey of the Adirondack region.  As part of this project he completed the first recorded ascent of Seward Mountain.  To complete his survey, he needed to know roughly how tall the mountain was.

One way to work out the height of a mountain was to take barometric readings at the top.  Since air pressure is lower the higher you climb, you can compare those numbers with readings taken from close to sea level.  By working out the difference, you can figure out the difference in elevation.

For the best accuracy, the readings should be from the same region and at the same time.  But synchronizing time can be a little tricky when you’re on the side of a mountain.  Fortunately for Colvin, in 1870 the head of the Dudley Observatory was George Washington Hough.

Hough was not only an astronomer, but also an inventor.  And his pride and joy was a self-reading and printing barometer, which could keep track of changes in the barometric pressure and keep record of when they happened.  So when Colvin came down from the mountain, he could send his notes to Hough, who would compare Colvin’s readings with his own records from the appropriate time.

Colvin took the results and presented a report at the Albany Institute.  Fortunately for us, he included the text of the letter he received from Hough:

Letter from George Washington Hough to Verplanck Colvin

Letter from George Washington Hough to Verplanck Colvin

The result was significantly lower than previous estimates, but not far off of the current measurements.  It’s a small thing, but it helped establish Colvin as a serious surveyor and helped him gain funding for his continued work in the Adirondacks.  And that is important for New York, because Colvin became the father of the Adirondack Park.

Immediately after this presenting this letter, Colvin began to describe the damage caused by lumbering that he had seen from Seward Mountain.  He proposed that the Adirondacks become a state park to protect the forest.  He cleverly tied the preservation of the forest land, which shielded lakes and snow packs, with the need for water in the Erie Canal.  It became a major theme of his work.  When he was later appointed the superintendent of the New York state land survey, he oversaw the creation of the Adirondack Forest Preserve in 1885.

Making New Mirrors

Proof of Concept for Silica Mirror (Thomson Papers, B#6, F001)

Proof of Concept for Silica Mirror, 36″ (Thomson Papers, B#6, F001)

This doesn’t look like much, but it was the start of something that was going to revolutionize the field of astronomy.  This is a disk of silicon dioxide, also known as silica.  Since it is made from very clean quartz sand, it is also known as “fused quartz”.  You can think of silica as being very pure glass without any additives.

Those additives serve a purpose.  They lower the melting temperature of the silica.  Without those, silica can require a furnace at 3,000 degrees Fahrenheit to work with.  But removing those additives means that you have a type of glass that is very resistant to changes in temperature.

One of the first people to see the advantages in this was Elihu Thomson, a scientist, engineer and businessman who founded the Thomson-Houston Electric Company.  This company later merged with Edison General Electric to create the General Electric company we’re familiar with today.

Since fused quartz is so resistant to heat, it has been used in high temperature applications like halogen lamps and furnaces.  It’s strong, so it has been used in bathyspheres and other high-pressure devices.  But Thomson was an avid amateur astronomer, and he saw a use for silica that others might have missed: telescope mirrors.

Since silica resists changing shape with heat, it could be used in unheated observatories that could get blistering hot or freezing cold without distorting the viewing.  It could also resist the heat produced by grinding and polishing, which made it easier and faster to work with that regular glass.  Mirrors could be produced faster and – more importantly – larger than ever before.

In the late 1920s, when George Hale convinced the Carnegie Institution to fund the construction of a new telescope for the Palomar Observatory, he was thinking big.  Hale had already worked on the largest telescope in the world: the 40-inch refracting telescope at Yerkes Observatory, 60-inch Hale reflecting telescope at Mount Wilson Observatory and 100-inch Hooker reflecting telescope at Mount Wilson.  For his next – and final – telescope, he would require a massive 200 inch mirror.

This was probably beyond the conventional technology of the time.  Hale needed to try something new.  He ended up turning to Elihu Thomson and his idea for a fused silica mirror.

The lump at the upper right was a proof of concept.  The next mirror would be a sixty inch disk, and no one had worked with silica on that scale before.  It required new techniques and the construction of new furnaces in Thomson’s Lynn, Massachusetts plant.

Construction of a experimental furnace for the 60-inch Palomar Mirror (Thomson Papers, B#6, F006a)

Construction of a experimental furnace for the 60-inch Palomar Mirror (Thomson Papers, B#6, F006a)

In the end, it took three years to produce two sixty-inch mirror.  The first mirror was of excellent quality, but it cracked during the cooling process.  The second mirror was marred by air bubbles.  Thomson and  General Electric had proven that large scale silica mirrors could be made, but that wasn’t enough.  Hale needed something produce quickly, and at a reliable price.

So the 200-inch mirror was not made in a Schenectady factory, but in Corning Glass works.  And instead of silica, it was made of Pyrex.  One of the first attempts at the 200-inch mirror is on display at the Corning Museum of Glass.

It’s a little frustrating, but it’s a good example of the difference between a new technology and a more mature technology.  Pyrex had been invented in the 1890s, about the same time that Thomson began experimenting with fused quartz.  But Thomson was a businessman, and a busy one.  There was no immediate need for silica mirrors, and the potential market seemed small.  General Electric had plenty of other things to do.

Corning invested more time and energy into Pyrex, and so they went into the process with more confidence.  They succeeded in six months when GE it had taken three years to not quite pull it off.


“A Deed of More Perilous and Romantic Courage has Perhaps Never Been Undertaken …”

Ormsby MacKnight Mitchel (1810-1862)

Ormsby MacKnight Mitchel (1810-1862)

Ormsby MacKnight Mitchel was a tireless scientist and engineer who deserves a share of the credit for shaping American astronomy.  He was an institution builder and a self-taught astronomer responsible for starting both the Cincinnati Observatory and our own Dudley Observatory.  He was also an  inventor, and his chronograph  allowed a single astronomer to both make observations and record the exact time the observation was made.  This made the star catalogs late 19th century possible.

But for all that, Mitchel is likely to be best remembered for something that has nothing to do with astronomy.

Mitchel helped found the Dudley Observatory and became the director, but he never set foot in the building.  That’s because the Civil War started before he made it to Albany.  Mitchel entered into the Federal Army with a reserve rank of brigadier general and organized defenses around Cincinnati, Ohio, then moved into Kentucky and Tennessee.

It was in Murfreesboro, Tennessee, in April of 1962 that Mitchel saw an opportunity.  He was not far from rebel-held Chattanooga.  He could take Chattanooga, but there was a rebel held railroad running from the city down to Atlanta, Georgia, that would bring up rebel reinforcements.  But if that railway was somehow destroyed, then Mitchel could hold Chattanooga and win a major victory.


James J. Andrews (1829-1862)

Mitchel didn’t have the troops to attack both Chattanooga and the well defended railway.  That meant it was time to get sneaky.  Mitchel worked out a plan with a civilian spy named  James J. Andrews.  The agent would lead two dozen Union soldiers in plain clothes down to Atlanta.  There they would steal a locomotive engine and flee back towards Chattanooga, destroying the railway bridges as they went.  Then they would shoot through Chattanooga and rejoin Mitchell’s army.

The plan started off without a hitch.  Andrews and his men slipped into Marietta, just north-west of Atlanta.   Meanwhile, Mitchel successfully took Huntsville, Alabama, which would be Andrews’ destination after the operation.   Two of Andrews’ men were accomplished engineers, and they slipped into an unattended train named The General, uncoupled it from the baggage cars and steamed off with their stolen engine.

Things fell apart not long thereafter.  Despite their haste, they were required to sit for twenty minutes on a side track to let another train pass.  This was enough time for the rebel troops in Atlanta to figure out what had happened and set off in pursuit with their own engine.  Andrews and his men had to abandon the plan and steam ahead as fast as possible to escape their pursuers.

What followed was a hundred mile railway chase which has become legendary in American history.  Dubbed The Great Locomotive Chase,  it captured the imagination of the American public.  The popular historian John Stevens Cabot Abbot wrote a breathless article about the raid for Harpers in 1865 from which I took my title, “Heroic Deeds of Heroic Men.”  It has been the subject of probably a dozen books, starting with Daring and Suffering by one of the participants, to the recent Stealing the General by Russell Bonds.  It was the inspiration for Buster Keaton’s 1926 movie “The General,” and in 1956 it became a Disney movie starring Fess Parker (AKA “Davey Crockett”) as James Andrews.

The Disney film got mixed reviews, likely because the ending was downbeat.  Andrews and his men ran out of fuel and had to abandon their engine.  They were rounded up and imprisoned. Eight, including Andrews, were eventually hanged.  Their mission failed, and Mitchel did not take Chattanooga.  He would die six months later of yellow fever.

The bravery and ingenuity of the men involved has not been forgotten.  When the Medal of Honor was created in 1863, one of the raiders named Jacob Parrott became the first recipient.  Unfortunately, James Andrews himself could not receive a posthumous awards since he was an espionage agent and not officially part of the military.  He is remembered on a monument at the Chattanooga National Cemetery.

Recovering the History of Women Computers

As an archivist, I’m not used to covering topical issues.  But the history of women computers in the field of science is suddenly getting a lot of attention.  The latest is the film “Hidden Figures,” which follows four African American women and their careers as mathematicians in Langley Memorial Aeronautical Laboratory’s computer pool.  It’s based on the book by Margot Lee Shetterly and it’s slated to hit theaters late this year.

I’ve already mentioned the documentary called The Computers, which focuses on the women who became the first programmers of ENIAC.  More general is the PBS documentary Top Secret Rosies about the women who did ballistics research during WWII:

All this comes as new research shows that women were basically marketed out of the field of computer science during the early days of home computing.  Starting in the mid eighties, the percentage of women in the field of computer science began to drop out of proportion with their presence in other STEM fields.   The dominate theory right now is that home PC’s were specifically marketed to the public as a boy’s toy, creating the perception that all computers and coding were part of the masculine realm for some reason.  This created the stereotype of the male computer geek, and also edged young women out of the discipline.  The discussion is well covered by the Planet Money podcast:

HENN: Now, it’s hard to say if this is straight-up sexism or computer makers just had data that boys were a more receptive audience, but whatever the reason, this fed on itself. In the mid-’80s, you could turn on the TV and see women doctors on “St. Elsewhere.” Claire Huxtable was a lawyer on “The Cosby Show” – cops? – “Cagney & Lacey.” But pretty much anytime a computer was turned on, it was a male nerd running it. Think “WarGames,” “Revenge Of The Nerds,” “Weird Science.”

[…]HENN: By the mid-’90s computer science departments had been transformed. Carnegie Mellon, which had one of the best programs in the country, was 93 percent men. The number of women entering the field had slowed to a trickle …

The focus now is on changing this perception.  As I pointed out last time, the history of American astronomy is intertwined with the history of computer science and women mathematicians.  Astronomy may be the path forward once again.