A while back, I was doing some research on the history of Mars. There were books in the University of Michigan Science library, and several occasions I went through the stacks looking for material. By happenstance, I found a book that contained something unusual.
Before I explain what was unusual, I need go into a little history. As you probably know, in the late 1800’s Percival Lowell (1855-1915) built an observatory near Flagstaff Arizona which became known as the Lowell Observatory. Lowell appointed himself director.
When astronomers of the time observed Mars, some saw lines on the surface. Many people believed these lines were canals, including Lowell. However a few astronomers were skeptical. For example, E. Walter Maunder; in 1903 he asked a group of school boys to draw sketches of Mars. The results of this experiment suggested that the canals might be an optical illusion.
To deal with such skepticism, Lowell asked two of his assistants, Vesto Slipher (1875-1969) and Carl Lampland (1873-1951) to take photographs of Mars. In 1905 there was a Mars opposition and an opportunity. However photographing the surface of Mars wasn’t easy. The films at the time were not very fast. Atmospheric distortions cause the image of Mars to move slightly, and without fast film, you are likely to get a blurry image.
Slipher and Lampland were up to the challenge. That May, Lampland had succeeded in taking a set of photos with surface detail. We know that Lampland showed the photos to Lowell and Lowell believed the photos proved the canals were real. We know this because of an announcement printed in the May 28, 1905 New York Times:
CAMBRIDGE, Mass., May 27.-A telegram was received at the Harvard Observatory tonight from Prof. Percival Lowell, Director of the Lowell Observatory at Flagstaff, Ariz., stating that the canals of Mars have been photographed there for the first time.
Several of them appear upon more than twenty negatives.
(This reflects the normal procedure at the time, if you had an important astronomical discovery, you sent a telegram to the Harvard Observatory).
Lowell sent prints to various people. A few days later Garrett Serviss (science writer for the Hearst Newspapers) examined some of the prints. He saw canals, but concluded that “the photographs are so small and the shadings on them so delicate, that it would be impossible to reproduce them in a newspaper.”
For this reason the photos never appeared in the New York Times or any other newspaper. Reproductions of the photos appeared in a few magazines. People did not see canals in the reproductions. Apparently whatever optical illusion caused people to see canals in the telescopic images of Mars and in the photographs, was not operating when people looked at the magazine reproductions (probably because they were too blurry). This encouraged Lowell’s critics, but also made Lowell more determined.
In 1907, Vesto’s younger brother Earl (1883-1964) arrived at the Lowell Observatory. Earl proves to be very talented, and produced a number of Mars photographs. Lowell believes some of these photographs show proof of canals. This time Lowell avoids the newspapers. He tries to publish these photos in a couple magazines as proof of his canal theories. But for rather complicated reasons, the photos are not published.
Earl shares Lowell’s belief in canals. He continues to believe in them long after Lowell’s death. Over the next 45 years Earl takes in excess of 100,000 Mars photographs. Earl believed that some of them showed canals and a few find their way into books or magazines.
About 1960, Earl took 19 of his best “canal” photos along with 11 Mars sketches and made a composite print. I don’t know how many copies he made, but he distributed these copies in an attempt to convince others.
Ironically the same year that Earl died, 1964, Mariner 4 was launched. In 1965 it made the first successful flyby of Mars and takes numerous photographs. When the photographs are analyzed, there was no evidence of canals.
Ok, lets go back to the Science Library. I was looking through the stacks and noticed two copies of a 1962 book by Earl Slipher. I knew that Earl was one of Lowell’s assistants, so I took them both to a table and looked through them. There were reproductions of a number of Earl’s Mars photographs. When I got to page 163, I noticed a photograph, but it was not a reproduction. A photograph had been glued onto the page. It was Earl’s composite of 30 Mars photos/sketches.
I checked page 163 of the other copy. It had the reproduction of the composite, nothing was glued into this copy. This was a bit odd, so I looked more carefully at these books. The book with the photograph glued onto page 163 had a sticker inside the front cover. I’ve seen these stickers before, they signify a book was a gift to the U-M library. This one said it was a gift from the “Lowell Observatory.”
A reasonable guess is Earl glued prints of his composite into copies of his book and sent them to various locations, including U of M. He worked at the Lowell Observatory until his death, which explains the sticker. There is a possible explanation for why Earl chose U of M to receive one of the copies. Earl made a number of his Mars observations at the Lamont-Hussey Observatory in South Africa in the 1950’s. And the Lamont-Hussey Observatory was operated by the University of Michigan for many years, including the period when Earl made his observations.
I went back and read the text on the previous page, page 162. The second paragraph was particularly revealing. Slipher states that the
History of the canal problem shows that every skilled observer who goes to the best available site for his observations has had no great difficulty of seeing and convincing himself of the reality of the canals. I am not aware of a single exception to this. Even some with small telescopes, when they journeyed to suitable places in the proper latitudes of the Earth, have met with convincing success.
This sounds similar to statements Lowell made. However, it is not hard to find observers who did not see Martian canals and it isn’t reasonable to dismiss all of them. The best example was the astronomer Edward Barnard. Barnard and Lowell were good friends who respected each other. Barnard was one of the best observers of the time, but Barnard was never able to see canals.
This might have been difficult for Lowell to explain, a good observer (Barnard) who couldn’t see canals. However Lowell was never short of explanations. According to Lowell, only people with “acute” vision were able to see the canals. He explained that Barnard had “sensitive” vision which allowed him to see dim objects, but not fine details on bright planets. It is unfortunate that Lowell never considered a better explanation, that the canals were optical illusions.
For further reading, these are the references I used in constructing this article:
------. May 28, 1905. “Photograph Mars Canals.” The New York Times.
------. 1954. Report of the International Mars Committee. E. C. Slipher and A. G. Wilson (secretaries). Flagstaff, Arizona: Lowell Observatory.
------. The Lowell Observatory Website (http://www.lowell.edu/).
Hoyt, William Graves. 1996. Lowell and Mars. Tucson Arizona: University of Arizona Press.
Sheehan, William and O’Meara, James Stephen. 2001. Mars: The Lure of the Red Planet. Amherst, New York: Prometheus Books.
Slipher, Earl C. 1962. The Photographic Story of Mars. Edited by John S Hall. Cambridge Massachusetts: Sky Publishing.
This is the book I was talking about. Note that only some copies have a photograph glued onto page 163.
Snyder, Dave. April 2001. “An Observational History of Mars, Part 1.” Reflections of the University Lowbrow Astronomers. (Both Part 1 and Part 2 are on-line at “An Observational History of Mars”).
------. May 2001. “An Observational History of Mars, Part 2.” Reflections of the University Lowbrow Astronomers. (Both Part 1 and Part 2 are on-line at “An Observational History of Mars”).