Monthly Archives: April, 2013

Andrew Abela’s Chart Chooser

Andrew Abela - Chart Chooser In Color

A question I am often asked is what chart is best for me to use?

First, think about what it is you want to show. Is it a relationship between two variables, a distribution, a comparison? The answer to this question will lead you to the right suite of charts that might be appropriate. Andrew Abela ( has developed a chart chooser to help with this exercise. [SOURCE]

Once you’ve answered the question of what you want to show and determined the right suite of charts that might be appropriate, the right answer to the question what is the right chart for my situation? will always be the same: whatever will be easiest for your audience to read. There’s an easy way to test this, which is to make your visual and share it with a friend or colleague. They don’t need any context; actually, it’s better if they don’t have any (this puts them in a position similar to your audience, who will always be less familiar with what you want to communicate than you are). Ask them to talk you through what they see: where they focus, what observations they make, what questions they have. This will help you to see if you are on the right track when it comes to whether what you want to communicate is coming across, or in the case that iteration is needed, where to focus your effort.

The meta-lessons here are 1) choose a visual display that’s appropriate for the data and information you are trying to show, and 2) seek feedback, there is tremendous value in getting a fresh perspective from someone less familiar with the data than you are to help you iterate for success. A related tip is to start with a blank piece of paper, which can be helpful as you try to determine the visual display that will work best as part of your early iterating process.

Do you have other resources or tips for choosing the right type of visual display? Leave a comment with your thoughts!



Illustrations from a Victorian Book on Magic (1897) – Part 3

Today is the third and final part of my series of selected images from a massive late 19th century tome entitled simply Magic, subtitled Stage Illusions and Scientific Diversions, including Trick Photography, compiled and edited by Albert A. Hopkins. The book takes a thorough tour through the popular magic tricks and illusions of the day, including along the way many delightfully surreal diagrams and illustrations.

I will warn you now that this third part of this blog will show some particularly great “decapitation” trick photographs.

(All images taken from the book housed at the Internet Archive, contributed by the California Digital Library.) [SOURCE]

Best Regards,







Illustrations from a Victorian Book on Magic (1897) – Part 2

Today is Part 2 of selected images from a massive late 19th century tome entitled simply Magic, subtitled Stage Illusions and Scientific Diversions, including Trick Photography, compiled and edited by Albert A. Hopkins. The book takes a thorough tour through the popular magic tricks and illusions of the day, including along the way many delightfully surreal diagrams and illustrations.

The third part of this blog will show some particularly great “decapitation” trick photographs.

(All images taken from the book housed at the Internet Archive, contributed by the California Digital Library.) [SOURCE]

Best Regards,





Illustrations from a Victorian Book on Magic (1897) – Part 1

The Great Houdini by Beryl Williams & Samuel Epstein I become interested in magic in the 5th grade of elementary school. Through Scholastic Books Services, I purchased The Great Houdini by Beryl Williams & Samuel Epstein for fifty cents. When I got home from school, I started reading the book and stayed up all night reading it until it was finished.

Over the years, I have visited the Houdini Museum in Niagara Falls, Canada (now burned down), visited his grave in New York, followed auctions of his memorabilia, and have read many books that probe deeper into his life. I occasionally do magic performances for my wife’s K-3 kids at the school she retired from.

So, to say the least, I truly do love magic.

Below, and over the next several blogs, are selected images from a massive late 19th century tome entitled simply Magic, subtitled Stage Illusions and Scientific Diversions, including Trick Photography, compiled and edited by Albert A. Hopkins. The book takes a thorough tour through the popular magic tricks and illusions of the day, including along the way many delightfully surreal diagrams and illustrations.

The third part of this blog will show some particularly great “decapitation” trick photographs.

(All images taken from the book housed at the Internet Archive, contributed by the California Digital Library.) [SOURCE]

Best Regards,





xkcd: Adobe Download Manager

Is this circular logic or recursive?

Adobe Updater

Social Distortion in Charts: The Venezuela Presidential Election 2013


Election authorities proclaimed Hugo Chavez’s handpicked successor Venezuela’s president-elect last Monday, despite his challenger’s demand for a recount.

“It was a result that was truly fair, constitutional and popular,” Nicolas Maduro Moros said, criticizing his opponent’s refusal to concede.

Maduro Moros secured 50.8% of votes in Sunday’s election, while opposition candidate Henrique Capriles Radonski won 49.0%, Venezuela’s National Electoral Council said Monday.

The South American country’s top election official certified the results at a ceremony in Caracas, saying Venezuela’s voting system had worked perfectly.

Social Distortion (“The Lie Factor”)

The “Lie Factor” is a value to describe the relation between the size of effect shown in a graphic and the size of effect shown in the data.

Edward Tufte, Professor at Yale University, defined the “Lie Factor” in his book “The Visual Display of Quantitative Information” in 1983. He stated the principle that

The representation of numbers, as physically measured on the surface of the graphic itself, should be directly proportional to the quantities represented.

[Tufte, 1991]

We will discuss more about Mr. Tufte’s work in future blogs.

The chart above is a good example of the Lie Factor. The election has a paper-thin margin of victory. Supporters of Radonski, as well as the World political community, are asking for a recount and an audit. However, if you were to look at the two vertical cylinders in the chart above, it would appear visually that the election was not even close.

Yes, it is a ridiculously truncated chart. So ridiculous that they had to change it soon after hilarity ensued on Twitter. [SOURCE]

But something happened that made me remember that most Bad Charts are created to purposely mislead the public: 7 people were killed in the protests following the election.

As a person who can read a chart (or numbers), you can tell that the results of Venezuelan elections were a really close call. So close, that the opposition candidate, Henrique Capriles Radonski, demanded a vote by vote recount, a position backed by the Organization of American States and the United States. People have gone to the streets to show support for their candidates, which is what lead to 7 people being killed on Tuesday, plus dozens injured, hundreds arrested, and property damage, including several universities. Capriles had to call off the rally planned for yesterday to demand a recount in fear of further violence. Instead he asked his supporters to go out to the streets every night at 8pm and bang pots and pans to show defiance. In response, Maduro asked his supporters to throw fireworks at the same time.

Decoding the Fire Diamond Sign


(Above) An NFPA 704 sign out in the wild. According to the  sign, whatever is behind that door is very, very dangerous and cannot be exposed  to water. (image: Flickr user johnwilliamsphd)

Cities are full of signs. Signs telling us where to go and how to get there;  signs suggesting things to buy and signs keeping us from where we shouldn’t be.  Every sign is a code of sorts, a graphic system linked to something else – an  idea, an instruction, a building. Typically, these codes are carefully designed  to be decipherable by as many people as possible – everyone, ideally. They  reduce meaning to its most essential components: RED=STOP. But occasionally in  cities, there are signs that aren’t intended to be read by everyone, coded  messages for specific agencies or civil service employees. These signs are  ubiquitous but largely indecipherable and mostly go unnoticed. One such sign is  NFPA 704 – perhaps better known as the “fire diamond.” [SOURCE]


(Above) A blank NFPA 704 panel (image: seton)

NFPA 704 is the American system for identifying hazardous  materials created by the National Fire Protection Association. It was first developed  in 1957 by the NFPA’s Sectional Committee on Classification, Labeling, and  Properties of Flammable Liquids “to safeguard the lives of those individuals who  may be concerned with fires occurring in an industrial plant or storage location  where the fire hazards of materials may not be readily apparent.” In 1961, the  NFPA formally adopted the primary-colored diamond design as a National standard,  providing emergency workers with a simple, readily recognized and decipherable  system of signage describing general hazards to help workers in planning a safe  and effective response.


(Above) Design regulations for the NFPA 704 standards (image:  NFPA)

These signs are found on chemical tanks, warehouse doors, and loading docks  all over the country – any industrial, commercial, or institutional building  that manufactures, processes, uses, or stores hazardous materials that “would  cause, or significantly contribute to an increased risk of serious injury,  incapacitating illness or increased risk of death.” They are exclusively used on  structures or containers; signage for vehicles carrying hazardous materials is  regulated by the Department of Transportation. Although the National Fire  Protection Agency standard describes the relative sizes of the diamonds and the  numbers, including the suggestion that diamonds used on building exteriors  measure no less than 15 inches by 15 inches, local authorities have final  jurisdiction over how the signs are implemented, including their location and  size.

The basic form is familiar to anyone who’s every had some sidewalk chalk and  a ball. A diamond divided into four smaller diamonds, each given a color code  and number to signify a specific hazard: the blue diamond is the health signal,  ranked according to the level of toxicity and effects of exposure to response  personnel; the red signifies the level of flammability, and the yellow indicates  reactivity. The white diamond is reserved for any other necessary information,  such as water reactivity, radioactivity, the need for protective equipment, or  specialized extinguishing agents. The number within each diamonds indicates the  severity of the threat, ranging from 0, indicating no hazard or unstable  materials, to 4, which indicates highly combustible, toxic, or reactive  materials that could cause death or major injury.


(Above) Symbols used for the white diamond (image: Safety  Sign)

With the exception of the poison and radiation symbols, NFPA 704 is almost  completely opaque to the average person and just fades into the background of  visual white noise produced by the modern American built environment. But to  those for whom they’re intended, the signs provide invaluable, and potentially   life-saving information. Other countries have their own unique standards,  such as the orange hazard symbols required on all European vehicles  carrying dangerous materials. Have you observed similar signs oversees? Are you  curious about other signs and symbols? Let me know in the comments!



DataViz History: The Ghost Map: Myth-Making and Evolution of the Ghost Map

The Earliest Spot Map of All

Dr. John Snow did not draw a map until December, 1854; the first spot map was produced in September of that year by Edmund Cooper, an engineer for the Metropolitan Commission of Sewers (see map below). Cooper’s investigation resulted from public complaints linking the sewers to the cholera outbreak. Rumors held sway that sewer works had disturbed the soil of an ancient pit where bodies had been buried during the plague of 1665. Many feared that this process had freed or generated noxious gases that caused the cholera. Some alleged further that cholera deaths had been especially numerous in houses next to gully-holes, the openings through which sewer gases were vented to the surface.[SOURCE]

In response, on Sept 26, 1854, the Commission held a special “court” in Greek Street, Soho, as The Times of London duly recorded the next day: “Mr Cooper had prepared a plan which accompanied his report, and on the plan a distinguishing mark was affixed, showing the houses in which death had occurred.” From his study of this map, and of the sewers themselves, Cooper concluded that the houses nearest the gully-holes had no greater number of deaths than houses not so situated. The sewers of the area where most of the deaths were clustered were in reasonable condition. The drains of the houses of the region were in generally bad condition — with many cesspools and deteriorating brickwork — and most of the houses had not taken advantage of the opportunity to connect their drains to the recently constructed sewers. Broad Street was served by two non-connecting sewers, a new one and an old one; but the numbers of deaths appeared to be equally divided between the parts of the street served by the two different sewers. Few deaths had occurred near the old plague-pit. The sewers that drained the plague-pit area flowed northward to Regent Street, where there had been few, if any, cases of cholera.

The chairman of the commission accordingly concluded, as reported by The Times of London, that “the sewers were not the cause of the cholera; that they were not in any way connected with the disease; but that the real cause of the calamitous occurrences in the locality … was the filthy and undrained state of the houses.” The commissioners expressed their hopes that these facts would be widely circulated to allay public fears.

In his report, Cooper added: “Since the outbreak, six men have been employed in these lines of sewers getting up information on this subject, all of whom, I am glad to state, are quite healthy, and entirely free from disease.” Thus, he suggested, sewer gases were unlikely to spread cholera.

Cooper’s plan appears to be the first cholera-death spot map of the Broad Street area. Moreover, his plan accounted for 316 deaths (all those recorded in the registrar general’s weekly returns to Sept 9), far more than the 83 deaths that Snow had investigated during the first week of September. It also appears from Cooper’s report that he, unlike Snow, used his map as an analytical investigative tool. Until Cooper had constructed and examined his map, he could not know whether or not more deaths had occurred close to the sewer gully holes. Indeed, he may have been the first 19th century cartographer to have used a disease map in this fashion.

Just as Snow had an agenda in drawing his maps (to implicate a contaminated pump), the sewer commission also had an agenda — to clear the gully holes and sewer excavations of suspicion. The sewers, they were happy to report, had done nothing to increase mortality in this fearful epidemic. Cooper called attention to the number of deaths in Broad Street, but apparently neither Cooper nor any of the other commissioners noticed any peculiar concentration of spots around the corner of Broad and Cambridge Streets (where the now-famous pump was located). Simply plotting deaths on a map did not lead the commission to Snow’s interpretation of the facts.

Edmund Cooper's Map

(Above) Edmund Cooper’s map of the Broad Street cholera epidemic made for the Metropolitan Commission of Sewers, September 1854. Inset: the Broad Street pump and surrounding addresses. Cooper designated each affected house by a large solid bar, and the cholera deaths occurring in each house by thin lines.

Snow’s investigation

The officials of St James’s parish (where in Golden Square is located) were aware that their locality had suffered a cholera outbreak of unusual intensity, about 500 deaths having occurred in the 10 days from Aug 31 to Sept 9, 1854, in an area of only a few square blocks. In November of that year, they appointed a cholera inquiry committee to examine the event, and asked Snow to join them. One of his tasks was to write a report on the local water supply, which he submitted on Dec 12, 1854. About a month later, Snow published a detailed monograph on the mode of communication of cholera, which included a discussion of the Broad Street outbreak.  Internal evidence suggests that Snow completed the account in his monograph before he wrote his report to the parish committee. In any event, the two accounts of his methods parallel are very similar, and accord with his brief, earlier account, published in Sept 23, 1854.

Snow had observed cholera first-hand in 1831 as an apprentice surgeon-apothecary, but he seems not to have questioned prevailing theories of cholera pathology and transmission until 1848-49, when he formulated a theory quite at odds with the then-dominant views. Snow argued that cholera was a localized disease of the gut, and that its symptoms were entirely the result of fluid loss. The causal agent, he reasoned, must enter by mouth, multiply within the gut, and then spread to others by the fecal-oral route. In his 1855 monograph he suggested that the structure of the unknown agent was that of a cell but, in the absence of microscopic evidence, he avoided speculation on its exact nature. While direct contact with contaminated bedclothes, for example, could explain cholera’s spread within a household and other confined spaces, Snow deduced that the transmission of the disease across greater distances was due to drinking water contaminated with raw sewage containing the specific cholera poison. Snow described two local outbreaks of cholera in south London in 1849 that seemed to suggest strongly a water-borne route.

When epidemic cholera next arrived in England in 1853-54, Snow realized that he had an opportunity to test his hypothesis on a grand scale. Two competing water companies had laid pipes up the same streets in several south London districts. In the 1848-49 epidemic, both companies had drawn upon water from the River Thames that had been contaminated by sewage. By 1853, one company (Southwark and Vauxhall) still supplied contaminated water, while the other company (Lambeth) had moved its intake source upstream to a fairly clean section of the river. When Snow learned of his change in the water supply, he realized that this arrangement constituted a superb natural experiment.  He undertook door-to-door investigations to relate cholera mortality to the source of water and found greater mortality among those drinking the water supplied by the Southwark and Vauxhall company, and made these data the centerpiece of the 1855 edition of his monograph. It was this investigation in south London that Snow suspended for several days at the beginning of September to investigate the severe localized outbreak near Golden Square.

Because he already had a hypothesis, Snow immediately investigated the water supply. The piped water was supplied by a company that drew its water from an unpolluted section of the Thames; and he knew from his own experience of living in the area that most residents preferred pump water. Moreover, his study of earlier outbreaks led him to conclude that a sharp localized outbreak pointed to a contaminated pump or well rather than a problem with the general water supply.

He turned his attention to the five pumps near Golden Square, finding that most of them contained impurities visible to the naked eye. By contrast, when Snow inspected the Broad Street pump water, on Sept 3, it looked clear; but a local resident reported that its water had smelled offensive just the day before. On Sept 5, Snow obtained from the General Register Office a list of the 83 deaths ascribed to cholera in the Golden Square area since Aug 31. In his own words:

On proceeding to the spot, I found that nearly all the deaths had taken place within a short distance of the [Broad Street] pump. There were only ten deaths in houses situated decidedly nearer to another street-pump. In five of these cases the families of the decreased persons informed me that they always sent to the pump in Broad Street, as they preferred the water to that of the pumps which were nearer. In three other cases, the deceased were children who went to school near the pump in Broad Street …

With regard to the deaths occurring in the locality belonging to the pump, there were 61 instances in which I was informed that the deceased persons used to drink the pump water from Broad Street, either constantly or occasionally …

The result of the inquiry, then, is, that there was been no particular outbreak or prevalence of cholera in this part of London except among the persons who were in the habit of drinking the water of the above-mentioned pump well.

I had an interview with the Board of Guardians of St James’s parish, on the evening of the 7th inst [Sept 7], and represented the above circumstances to them. In consequence of what I said, the handle of the pump was removed on the following day.

Thus, Snow’s initial suspicion of the Broad Street pump was a deduction based on his intensive earlier study of similar cholera outbreaks, not an induction arrived at primarily from the geographical facts of the case. While Snow was clearly thinking in topographical terms (visualizing the location of houses where deaths occurred in relation to the placement of pumps), in the case that he presented to the parish officials he neither said nor alluded to the idea that a map had been instrumental in the discovery of the source of the outbreak.

Snow first exhibited a cholera spot map (see below) (with small black bars indicating deaths) of the Broad Street area at a meeting of the Epidemiological Society of London on Dec 4, 1854, nearly 3 months after his first investigation. He had in the interim made two more local inquiries in the Broad Street area, though one was hampered by the large number of local residents who had fled the region. By December, Snow had gathered data on 616 deaths, but because he did not know the exact address of some residents of St James’s parish who had died outside the district, his map had only 574 bars.

Snow may have realized that a spot map would be a useful illustration for his report to the parish committee and for his own book. The first edition of On the mode of communication of cholera, published in 1849, contained no maps and only one table.  By 1854 Snow had seen the excellent map in Shapter’s work on the cholera in Exeter, which Shapter included as a frontispiece but hardly discussed in his text.  Shapter’s book, which Snow cited in the second edition of his own work, may have persuaded Snow of the value of a map as an illustration.

Snow published two slightly different versions of his map, of which the map published in his cholera monograph appears to be the earlier. By the time the parish report was published 6 months later, Snow had made a few revisions. The most important was the addition of a dotted line enclosing the area that was closer to the Broad Street pump (in walking distance) than to any other street pump (see below). Such an equidistance line dividing a map into regions is called a Voronoi diagram, and Snow’s second map has been credited with being the earliest use of this device. The map with the Voronoi diagram most closely mirrors Snow’s narrative account of his investigation on the spot; and the text of his report to the parish committee is altered from the version that appeared in the monograph to refer to this new feature of the map.  This variation between Snow’s two maps lends further support to the hypothesis that he compiled them for illustrative rather than investigative purposes.  As a result of his two later investigations on the spot, Snow had amassed even more data to show that most people who died of cholera, but who lived outside the Voronoi area, had nonetheless drunk water from the Broad Street pump.

Besides the Voronoi diagram, Snow made an apparently small change that later proved important. In his first map, Snow had located the Broad Street pump in the wrong place, in front of the Newcastle Arms, the public house on the corner (still there in what is now Broadwick Street but today named after John Snow) rather than adjacent to the house next door at number 40. If Snow ever saw the more accurate government maps that we will describe below, he would have discovered that the spot at which he showed the pump was actually occupied by a sewer grating. When he revised his map, he moved the pump 24 feet to the west, to its correct location.

Snow also modified the map in the parish report in several minor ways. He altered the political boundary lines to better show the area within which deaths had occurred, and added subdistrict division lines. He included one distant pump that had not been shown on his first map, raising the total number of pumps depicted from 13 to 14. He missed a more distant pump, in Nag’s Head Yard, that was shown on the other maps we will discuss below.

Because Snow was preoccupied with his more important south London study, his initial investigation in Broad Street was brief. Another member of the parish inquiry committee, Rev Henry Whitehead, eventually discovered the probable cause of the contamination in the water of the pump. In April, 1855, Whitehead learned that a child at 40 Broad Street had become ill with “diarrhea” at the end of August, and died on Sept 2. Her mother had washed the soiled nappies and disposed of the water through the house drains — drains that were later shown to run a few feet from the well of the pump. An earlier excavation of the Broad Street pump well, in the autumn of 1854, had found the brick lining apparently intact. But, in late April, 1855, a more careful excavation showed that both the house drain and the pump well had decayed brickwork that permitted percolation of fluid from the former to the latter. Snow, unaware of the death of this child, drew only four bars at number 40. Later maps incorporated Whitehead’s data and showed five bars.

MSU Snows Map

(Above) Snow’s spot map of the Golden Square outbreak, 1854.

MSU Snows Spot Map

(Above) Detail from Snow’s spot map of the Golden Square outbreak showing area enclosed within the Voronoi network diagram. Snow’s original dotted line to denote equidistance between the Broad Street pump and the nearest alternative pump for procuring water has been replaced by a solid line for legibility. Fold lines and tear in original (adapted from CIC, between 106 and 07).

Snow's Spot Map - Detail

(Above left) Snow’s spot map, detail of area around the Broad Street pump (from  MCC2). (Above right) Snow’s spot map, detail of area around the Broad Street pump. The finely dotted Voronoi line is in the lower half; the symbol for the Broad Street pump-circle around black dot-has been repositioned to its correct location opposite no. 40 Broad Street (from CIC, between 106 and 107).

The Later “Government” Maps

The Committee on Scientific Inquiries of the General Board of Health, the national body charged with investigating the cholera epidemic, also supervised the drawing of a spot map of the Broad Street area. This was printed both in the St James’s parish report and in the more voluminous central government report. The precise relation between this map and Cooper’s earlier map is unknown; the Parish report refers to their map as “constructed on the authority of the one published in Mr Cooper’s Report”, but it is unclear whether this refers to the map as a whole, or only to the diagram of the sewers.

The later government maps were (like Cooper’s map) more detailed than Snow’s. For example, clusters of bars depicting many deaths in the same house were better drawn, compared with Snow’s map where some of the bars appeared to be at quite a distance from the actual location of the house. The houses were numbered, making comparisons between the map and other data easier. The government investigators also had the advantage of Whitehead’s discovery of the “index case” of the infant at number 40, Broad Street — that house shows five bars on the government map (see below), compared with four bars on Snow’s two maps (see above).

But having a better map to work from assured neither adoption of Snow’s theory nor agreement among those who studied the map. The parish committee, as we have seen, supported Snow’s claim that the Broad Street pump was the source of contamination, even though they held back from endorsing Snow’s entire theory of the pathophysiology of cholera. By publishing the government map, they thought they were providing additional evidence in Snow’s favor. By contrast, the Committee on Scientific Inquiries of the General Board of Health flatly rejected the pump theory and insisted that some concentrated noxious atmospheric influence, no doubt emanating from putrefying organic matter, was the cause of the Golden Square outbreak. The committee’s thinking paralleled that of another highly respected cholera authority, Edmund A Parkes:

“On examining map given by Dr Snow, it would clearly appear that the center of the outburst was a spot in Broad-street, close to which is the accused pump; and that cases were scattered all round this nearly in a circle, becoming less numerous as the exterior of the circle is approached. This certainly looks more like the effect of an atmospheric cause than any other; if it were owing to the water, why should not the cholera have prevailed equally everywhere where the water was drunk? Dr Snow anticipates this by supposing that those nearest the pump made most use of it; but persons who lived at a greater distance, though they came farther for the water, would still take as much of it … There are, indeed, so many pumps in this district, that wherever the outbreak had taken place, it would most probably have had one pump or another in its vicinity.”

It was not unusual at that time to see spot maps invoked in defense of a miasmatist theory of disease transmission. As early as 1798, Seaman used two spot maps to illustrate a report on deaths from yellow fever in New York [16], and these maps were later used by both contagionists and anti-contagionists to advance their respective causes.

Cooper marked with a thick bar each house in which death from cholera had occurred, and indicated only by thin lines how many deaths had occurred in each house. Thus households that had suffered one and ten deaths, respectively, appeared similar on quick inspection. For Cooper, the cause of cholera was obviously a generalized environmental influence, and so what mattered were the locations at which deaths had occurred. By contrast, Snow’s theory required the unit of analysis to be the individual, since in any house, some might have drunk the pump water and some not. Nonetheless, the Board of Health adopted Snow’s method of marking the frequency of individual deaths (which was the standard method of the day), but without accepting Snow’s theory.

The different conclusions drawn by the two official investigations in Broad Street are reflected in the one change that the parish committee made in the government map. The Board of Health, in constructing their map, saw no reason to focus on the Broad Street pump. By contrast, on the otherwise identical map included in the parish report, a circle was drawn, of a radius of 210 yards, with the Broad Street pump at the center. This circle defined the “cholera area”, within which the mortality was greatest. The parish committee apparently did not realize that by depicting the high-risk zone as circular, they were inviting a rebuttal such as Parkes’, that the diffusion of an impure atmospheric influence would best explain the distribution of deaths. By contrast, Snow in drawing his irregularly-shaped area based on walking distance to the nearest pump, neatly turned aside such a criticism.

The government map-makers disagreed among themselves in one other way. The local inspectors appointed by the General Board of Health to investigate the Broad Street outbreak, Drs Fraser, Ludlow, and Hughes, found themselves walking the pavements at the same time that Cooper was making his survey of the sewers, and the two groups exchanged information on at least one occasion. But, while Cooper thought that his own map conclusively proved that the sewers were not to blame for the epidemic, the Board inspectors stated in their report that the gully-holes and their bad smells had been a major source of the cholera.  Neither Cooper nor the Board inspectors offered any sort of numerical analysis in defense of their respective interpretations.

MSU Whitehead Map

(Above) The General Board of Health map used by CIC, with Whitehead’s “cholera area” indicated by a circle (CIC, between 96 and 97).


It appears that John Snow thought geographically, but did not use a map to discover the likely source of the Broad Street outbreak. Snow’s map of the epidemic area was simply the visual representation of a deduction from a theory of transmission developed earlier, which in turn was grounded in a theory of the pathology of cholera as primarily a disorder of the gastrointestinal tract. But, since 1902, when reproductions of his maps began to appear in textbooks of hygiene and public health, our fascination with the map has tended to distort our understanding of his methods. As our survey of the government Broad Street maps has shown, the mere act of seeing data arranged graphically in space yields no new understanding without the support of a pathological theory.

One sees an echo of Snow the mapmaker, without the corresponding appreciation of Snow the thinker, in today’s “desktop mapping revolution” among public-health investigators, both lay and professional. Geographic information systems (GIS) are in vogue to show the geographical distribution of individual or aggregate morbidity or mortality. GIS and spatioanalytical research in general has great potential when used to test specific biologically plausible hypotheses about causes of disease. But these same methods can be dangerously misleading when used merely to generate information about geographical and epidemiological associations. Associative data, plotted in the form of a highly sophisticated and accurate map, may easily seduce us into concluding that we have learned something about the cause of disease. Resulting claims about disease “hot spots” may create unjustified worry and distract attention from solid but less visually appealing lines of research. If the methodological assumptions underlying these uses of GIS are correct, Edmund Cooper and not John Snow would have been credited with unraveling the Broad Street cholera outbreak.

As the tale of the Broad Street pump has been transformed into an anecdote resembling an urban legend, a recurring theme represents Snow as a clear-eyed modern thinker who saw the facts, and was opposed by defenders of ancient preconceived theories. But it misrepresents history, and does Snow an injustice, to imagine that he was not guided every bit as much by his own theory as his opponents were by theirs.

Visionary Architect Paolo Soleri Has Died at 93

399488Visionary architect Paolo Soleri, the Italian-born designer of the experimental city called Arcosanti in the high desert 60 miles north of Phoenix, died last Tuesday. He was 93. [SOURCE]

Soleri, one of the few remaining direct disciples of Frank Lloyd Wright, actually saw few of his projects built. But his exalted manifestos on a revolutionary lifestyle of complex but compact cities where cars are not needed and more of the natural landscape is preserved made him one of the most recognized names in architecture and design.

Few of his projects have been built, but it was his exalted manifestos that made him one of the most recognized names in architecture and design.

“If you are truly concerned about the problems of pollution, waste, energy depletion, land, water, air and biological conservation, poverty, segregation, intolerance, population containment, fear and disillusionment: Join us,” says the poster at Arcosanti’s entrance.

Just off Interstate 17 in Cordes Junction, Arcosanti is an urban project that explores the possibilities of future city life in concrete and steel. Soleri envisioned more than 5,000 people living in the complex. It never achieved Soleri’s full vision, though it continues to operate and evolve with his goals in mind.

Soleri’s impact can also be seen — and heard — across the Valley. Among his completed projects is a $3.5million pedestrian bridge in Scottsdale, Soleri Bridge and Plaza, southwest of Camelback and Scottsdale roads. It is the only completed bridge of the hundreds he designed.

Soleri Bells

And thousands of Valley residents treasure their “Soleri Bells,” unique cast-bronze wind-bells that are prized for their purity of tone. Soleri began designing and selling them half a century ago to finance Arcosanti.

Valley architect Will Bruder likened Soleri to Leonardo da Vinci, the prolific Renaissance painter, sculptor and architect, for his breadth of work on paper and his influential ideas.

“I’m not blowing smoke when I say he was of that stature,” Bruder said. “He’s more widely known in the world than Arizona by far. He will be remembered for hundreds of years.”

Bruder, who came to Arizona to work with Soleri in 1967 and 1968, spent last Wednesday morning visiting Soleri at his home in Paradise Valley, where he had taken to staying in bed.

“Paolo taught me about the ordinary becoming extraordinary,” Bruder said.

He added that the celebrated architecture of Burton Barr Central Library in Phoenix, which Bruder designed, would not have come about without Soleri’s input on materials and design.

Soleri studied with Wright at Taliesin West from 1947 to 1949. Yet he disagreed with the master architect’s vision of a utopian suburbia reliant on the automobile, a concept Wright called “Broadacre City.”

“We must build up, not out,” Soleri told The Arizona Republic in 2011.


“The problem is the present design of cities only a few stories high, stretching outward in unwieldy sprawl for miles. As a result of their sprawl, they literally transform the Earth, turning farms into parking lots, and waste enormous amounts of time and energy transporting people, goods and services over their expanses.”

Soleri received his first commission with architect Mark Mills in 1949 from heiress Nora Woods to build the “Dome House” in Cave Creek. He married Woods’ daughter, Colly, the same year. They had two daughters, Kristine and Daniela. Colly Soleri died in 1982.

Born in Turin, Italy, Paolo Soleri returned to his home country in 1950. There, he studied solar energy and completed several architectural commissions, including a lauded sculptural-ceramics factory on the coast south of Naples.

He returned to Arizona in 1956, the same year he founded the Cosanti Foundation. “Cosanti” combines the Italian words, “cosa” (things) and “anti” (against).


Soleri distrusted affluent suburbia. But as the Valley grew, urban sprawl surrounded his Paradise Valley home — a 5-acre compound called Cosanti.

Cosanti has grown amid the paloverde trees, mesquite, prickly pear and saguaro. A collection of concrete domes set into the Earth dot the property at 6433 E. Doubletree Ranch Road.

It also features a foundry that produces the famous Soleri Bells. Each is cast in bronze or clay and is unique. Ranging in price from $29 to $3,000, they have been the main financial support for Soleri and his projects.

Implementing Wright’s idea of using apprentices, people work at the foundries at Cosanti and Arcosanti pouring about 600 pounds of molten bronze a day into the sand molds to make the bells.


Until recently, Soleri had divided his time between the weathered, wood-frame house on the Cosanti property and his Arcosanti creation north of the Valley.

Soleri began constructing Arcosanti in 1970 on 860 acres of desert outside Phoenix.

The model city, as it was envisioned, was based on a philosophy of “arcology,” or a combination of architecture and ecology. The compact beehive complex where human activity is surrounded by the desert’s natural beauty was proclaimed by Newsweek magazine in 1976 as “probably the most important experiment undertaken in our time.”

But no one could ever judge the experiment because the honeycomb buildings are less than 5 percent complete, and only 55 people reside there.


He retired in 2011 as the president of the Cosanti Foundation. The new president is Jeff Stein, a former dean of the Boston Architectural College. Stein, who worked for Soleri at Arcosanti during the 1970s and ’80s, hopes to revitalize the “accidental community.”

Stein said that though Soleri was disappointed Arcosanti wasn’t more realized, he did have patience in the process of building sustainable life in a new city. Arcosanti is not an “instant culture,” he said, created by resort developers flush with money.

“So, 40 years ago, where I’m talking right now was a mesa top,” Stein said from Arcosanti. “In another 40 years, it will be transformed that much more. Forty years ago, Phoenix didn’t seem like much, and in the first 40 years, neither did Tokyo or London or Chicago.


“(Soleri) was very realistic about the speed of construction here and why it was so slow and what it meant in the global conversation of developing cities.”

One project, completed through what Soleri called “no pushing or pulling” of his own, was the Soleri Bridge and Plaza. At $3.5 million, the bridge was the largest project ever undertaken by Scottsdale Public Art, the city-subsidized group that oversees public-art projects and events in the city.

The bridge took 20 years from concept to completion, largely because of financial issues. Dedicated in December 2010, the span was designed as a pedestrian passage and gathering place.

The 130-foot-long bridge widens from 18 to 27 feet and opens onto a 22,000-square-foot plaza, which has been a featured setting for several art and tourism events.

Most striking are two 64-foot brushed-steel pylons that generate a light beam on the walking surface of the bridge to mark solar events. A second set of 22-foot pylons set in the plaza house Soleri’s cast-bronze bells. The plaza features ten 8-foot-high concrete panels etched with Soleri designs.

“I wasn’t pushing or pulling for this,” he said at the dedication. “But when you come up with a concept, you do like to develop it. You do like to stay with it. That it serves as a sundial was also important. … We are so (disconnected) from our past. The sun is just something that happens. It’s not our business. But it is our business. We are the ‘big bang’ in development. We should be reminded of how we are connected with something that happened 12 billion years ago.”

A private burial will be held at Arcosanti, and a public memorial service will be held later this year.

DataViz History: The Ghost Map: Building a Case and The Pump Handle

pump2Dr. John Snow is credited with taking bold action when he sensed that contaminated water from the public pump on Broad Street was the cause of deadly cholera during the 1854 outbreak in London. Here is what he wrote of his legendary action on September 7, 1854. [SOURCE]


“I had an interview with the Board of Guardians of St. James’s parish, on the evening of Thursday, 7th September, and represented the above circumstances to them. In consequence of what I said, the handle of the pump was removed on the following day.”

– John Snow in his 1855 book

So who was the parish Board of Guardians and why did they respond as they did to Dr. Snow’s recommendation?


In England, the parish is the fundamental tier of local government. Saint James’s parish encompassed the region serviced by the Broad Street pump. The Board of Guardians was elected by local citizens, but only those who owned property, thereby excluding many ordinary people. The voters were usually small tradesmen or shopkeepers who were concerned with public safety and order. The Board of Guardians was responsible, among other concerns, for maintaining public health, but relied on the advice of medical practitioners such as Dr. Snow.

There were several views of what happened on September 7, 1854 when Dr. John Snow spoke to the Board of Guardians at the Vestry Hall near his home and the impact thereafter on the Broad Street outbreak.


Snow’s good friend, Dr. Benjamin Richardson, wrote years later in 1858 of the September 7th meeting.

“When the Vestry (the term used for a committee of members elected to administer the temporal affairs of a parish) men were in solemn deliberation they were called to consider a new suggestion. A stranger had asked in a modest speech for a brief hearing. Dr. Snow, the stranger, was admitted, and in a few words explained his view of the ‘head and front of the offending’. He had fixed his attention on the Broad Street pump as the source and center of the calamity. He advised the removal of the pump handle as the grand prescription. The Vestry was incredulous but had the good sense to carry out the advice. The pump handle was removed and the plague was stayed. There arose, hereupon, much discussion among the learned… but it matters little for the plague was stayed.”


lankester1862In 1866, twelve years after the event, Dr. Edwin Lankester wrote further of the pump handle incident. He was a member of a local group that looked into the causes of the Broad Street outbreak, and was later to become the first medical officer of health for the St. James’s district (the area where the outbreak occurred.

“The Board of Guardians met to consult as to what ought to be done. Of that meeting, the late Dr. Snow demanded an audience. He was admitted and gave it as his opinion that the pump in Broad Street, and that pump alone, was the cause of all the pestilence. He was not believed — not a member of his own profession, not an individual in the parish believed that Snow was right. But the pump was closed nevertheless and the plague was stayed.”


At the time of the Broad Street pump outbreak, Reverend Henry Whitehead was a 29-year-old cleric at a church in the Broad Street area. He became interested in the epidemic and conducted his own investigation, independent of Dr. Snow.

The Index Case?

mother_infantRev. Whitehead may have discovered the origin of the Broad Street pump outbreak, which started on August 30, 1854. An infant girl at 40 Broad Street near the pump had an attack of diarrhea on August 28-29 that lead to her death on September 2nd. The mother described to Rev. Whitehead how, during her baby’s illness, she had steeped its soiled napkins in pails of water and had emptied some of these into the cesspool at the front of the house. Whitehead was struck by the dangerous proximity of the cesspool to the pump well and convinced a government engineer to examine the area. This examination revealed the seepage of fecal matter through the decayed brickwork of the 40broadstreet_smallcesspool to the well which was less than three feet away. If the child had died of cholera (which Whitehead supposed), then this likely would have been the index case that started the Broad Street pump outbreak.

For more on the index case at 40 Broad Street, click here.

Reverend Whitehead’s views on the effects of the Board of Guardians removing the pump handle were presented in 1867, thirteen years after the outbreak had occurred.

“It is commonly supposed and sometimes asserted even at meetings of Medical Societies that the Broad Street outbreak of cholera in 1854 was arrested in mid-career by the closing of the pump in that street. That this is a mistake is sufficiently shown by the following table which, though incomplete, proves that the outbreak had already reached its climax, and had been steadily on the decline for several days before the pump-handle was removed.”

The table he presented showed how the number of fatal cholera attacks had diminished from 142 on September 1st, to 14 on September 8th, the day on which the pump was closed. Thereafter the new fatal cholera cases fell to single figures and slowly dwindled away.

Whitehead went on in his presentation.

“I must not omit to mention that if the removal of the pump-handle had nothing to do with checking the outbreak which had already run its course, it had probably everything to do with preventing a new outbreak, for the father of the infant, who slept in the same kitchen, was attacked with cholera on the very day (September 8th) on which the pump-handle was removed. There can be no doubt that his discharges found their way into the cesspool and thence to the well. But, thanks to Dr. Snow, the handle was then gone.”


A month after the September 8th removal of the pump handle, Dr. Snow spoke of his views on cholera before the Medical Society of London on October 14, 1854. An account of his talk appeared in the October 21st issue of the The Lancet.


Was his action important, based on sound logic and understanding of the local situation? Or did John Snow and the Board of Guardians over-react?

Contemporary epidemiologists view removing the pump handle as appropriate, and honor Snow’s action to safeguard the public, even in the face of biological and epidemiological uncertainty.

Next: Myth-Making and Evolution of the Ghost Map


Brody H et al. The Pharos 62(1), 2-8, 1999.

Chave, SPW. Medical History 11(2), 92-109, 1958.

English MP. Victorian Values — The Live and Times of Dr. Edwin Lankester, 1990.

Rivett, G. The Development of the London Hospital System, 1986.

The Lancet 67, 339-41, 1854.


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