« November 2007 | Main | January 2008 »

Monday, December 31, 2007

Fourmilab Server Farm: One Year Uptime

On the last day of 2007, the Fourmilab server farm reached the milestone of all machines which provide public services (Web, FTP, HotBits, etc.) having run for one year or more without a reboot or other system-wide service outage. The dual redundant power supplies of the Dell PowerEdge 1850 principal servers allowed the swap-out of an Uninterruptible Power Source (UPS) which failed to live up to its name without the need to shut down the servers to which it provided partial power.

 Host name  Function  Uptime as of 2007-12-31 
server1 Active public server 365 days, 10:31 hours
server0 Backup public server 722 days, 17:03 hours
server3  Test/administration server  378 days, 12:57 hours
hotbits0 HotBits generator 0 463 days, 10:12 hours
hotbits1 HotBits generator 1 428 days, 22:42 hours

Some people berate sites which rack up lengthy uptime records, claiming that this indicates neglect of preventive software maintenance, in particular keeping systems up to “current patch level”. Now, this is largely an instance of intellectual corruption due to Microsoft, where updating a music player requires rebooting a running system, but some Linux users also assume that frequent kernel updates and reboots to install them are essential for a secure system. Fourmilab's philosophy is different—on server farm machines, essentially the only component from the Linux software distribution used in the critical path is the kernel. Everything else: Web, FTP, mail, DNS, and other servers are built from source which resides in the server's private “/server” partition and, in keeping with the Unix tradition, any of these components can be updated as required simply by restarting it—no system reboot is required.

When a security or other update to one of the public server packages is released, I build it from source and test it on server3, the “Test/administration server”, which is actually a 6 year old laptop with a software configuration identical to the production servers. After testing, the update is deployed on the active and backup production servers with rdist, then put into production by restarting the server process on these machines; the interruption to public requests due to such a restart is on the order of one second. I generally install server updates on the active server first and leave the previous version on the backup server until I'm confident the new release is working well. That way, should the update crash or otherwise become nonresponsive under the real-world load, the load balancer will automatically fail over to the previous version running on the backup server.

The Fourmilab firewall is configured to only allow packets from the Internet to reach server farm machines on the ports on which these locally-built server processes listen; all other incoming traffic is discarded, so potentially vulnerable components from the Linux distribution, even if they were listening on some port, cannot be accessed from off-site by would-be attackers.

Posted at 16:45 Permalink

Sunday, December 30, 2007

Animal Magnetism: Not a Snake

notasnake.jpg This is not a snake. I know—“If it looks like a snake, and it slithers like a snake…”, but when's the last a time a snake blinked its eyes at you?

Details of my May 2007 encounter with this confusing creature have just been posted on the new “Not a Snake” page of the Animal Magnetism section of the site.

Sherisson.jpg Update: On Moon Day (July 20th) 2007, thunderheads towered so high above the Jura mountains that in mid-afternoon it was as dark as dusk. So dark, in fact, that a usually nocturnal hedgehog emerged from its den and was spotted walking along the side of a road. I've added a picture I took on this occasion to the hedgehog page of Animal Magnetism. (2007-12-31 19:58 UTC)

Posted at 17:57 Permalink

Friday, December 28, 2007

Reading List: Great Feuds in Mathematics

Hellman, Hal. Great Feuds in Mathematics. Hoboken, NJ: John Wiley & Sons, 2006. ISBN 0-471-64877-9.
Since antiquity, many philosophers have looked upon mathematics as one thing, perhaps the only thing, that we can know for sure, “the last fortress of certitude” (p. 200). Certainly then, mathematicians must be dispassionate explorers of this frontier of knowledge, and mathematical research a grand collaborative endeavour, building upon the work of the past and weaving the various threads of inquiry into a seamless intellectual fabric. Well, not exactly….

Mathematicians are human, and mathematical research is a human activity like any other, so regardless of the austere crystalline perfection of the final product, the process of getting there can be as messy, contentious, and consequently entertaining as any other enterprise undertaken by talking apes. This book chronicles ten of the most significant and savage disputes in the history of mathematics. The bones of contention vary from the tried-and-true question of priority (Tartaglia vs. Cardano on the solution to cubic polynomials, Newton vs. Leibniz on the origin of the differential and integral calculus), the relation of mathematics to the physical sciences (Sylvester vs. Huxley), the legitimacy of the infinite in mathematics (Kronecker vs. Cantor, Borel vs. Zermelo), the proper foundation for mathematics (Poincaré vs. Russell, Hilbert vs. Brouwer), and even sibling rivalry (Jakob vs. Johann Bernoulli). A final chapter recounts the incessantly disputed question of whether mathematicians discover structures that are “out there” (as John D. Barrow puts it, “Pi in the Sky”) or invent what is ultimately as much a human construct as music or literature.

The focus is primarily on people and events, less so on the mathematical questions behind the conflict; if you're unfamiliar with the issues involved, you may want to look them up in other references. The stories presented here are an excellent antidote to the retrospective view of many accounts which present mathematical history as a steady march forward, with each generation building upon the work of the previous. The reality is much more messy, with the directions of inquiry chosen for reasons of ego and national pride as often as inherent merit, and the paths not taken often as interesting as those which were. Even if you believe (as I do) that mathematics is “out there”, the human struggle to discover and figure out how it all fits together is interesting and ultimately inspiring, and this book provides a glimpse into that ongoing quest.

Posted at 16:22 Permalink

Tuesday, December 25, 2007

Reading List: Gastroanomalies

Lileks, James. Gastroanomalies. New York: Crown Publishers, 2007. ISBN 0-307-38307-5.
Should you find this delightful book under your tree this Christmas Day, let me offer you this simple plea. Do not curl up with it late at night after the festivities are over and you're winding down for the night. If you do:

  1. You will not get to sleep until you've finished it.
  2. Your hearty guffaws will keep everybody else awake as well.
  3. And finally, when you do drift off to sleep, visions of the culinary concoctions collected here may impede digestion of your holiday repast.

This sequel to The Gallery of Regrettable Food (April 2004) presents hundreds of examples of tasty treats from cookbooks and popular magazines from the 1930s through the 1960s. Perusal of these execrable entrées will make it immediately obvious why the advertising of the era featured so many patent remedies for each and every part of the alimentary canal. Most illustrations are in ghastly colour, with a few in merciful black and white. It wasn't just Americans who outdid themselves crafting dishes in the kitchen to do themselves in at the dinner table—a chapter is devoted to Australian delicacies, including some of the myriad ways to consume “baiycun”. There's something for everybody: mathematicians will savour the countably infinite beans-and-franks open-face sandwich (p. 95), goths will delight in discovering the dish Satan always brings to the pot luck (p. 21), political wonks need no longer wonder which appetiser won the personal endorsement of Earl Warren (p. 23), movie buffs will finally learn the favourite Bisquick recipes of Joan Crawford, Clark Gable, Bing Crosby, and Bette Davis (pp. 149–153), and all of the rest of us who've spent hours in the kitchen trying to replicate grandma's chicken feet soup will find the secret revealed here (p. 41). Revel in the rediscovery of aspic: the lost secret of turning unidentifiable food fragments into a gourmet treat by entombing them in jiggly meat-flavoured Jello-O. Bon appétit!

Many other vintage images of all kinds are available on the author's Web site.

Posted at 15:17 Permalink

Friday, December 21, 2007

Reading List: The Rocketbelt Caper

Brown, Paul. The Rocketbelt Caper. Newcastle upon Tyne: Tonto Press, 2007. ISBN 0-9552183-7-3.
Few things are as iconic of the 21st century imagined by visionaries and science fictioneers of the 20th as the personal rocketbelt: just strap one on and take to the air, without complications such as wings, propellers, pilots, fuselage, or landing gear. Flying belts were a fixture of Buck Rogers comic strips and movie serials, and in 1965 Isaac Asimov predicted that by 1990 office workers would beat the traffic by commuting to work in their personal rocketbelts.

The possibilities of a personal flying machine did not escape the military, which imagined infantry soaring above the battlefield and outflanking antiquated tanks and troops on the ground. In the 1950s, engineers at the Bell Aircraft Corporation, builders of the X-1, the first plane to break the sound barrier, built prototypes of rocketbelts powered by monopropellant hydrogen peroxide, and eventually won a U.S. Army contract to demonstrate such a device. On April 20th, 1961, the first free flight occurred, and a public demonstration was performed the following June 8th. The rocketbelt was an immediate sensation. The Bell rocketbelt appeared in the James Bond film Thunderball, was showcased at the 1964 World's Fair in New York, at Disneyland, and at the first Super Bowl of American football in 1967. Although able to fly only twenty-odd seconds and reach an altitude of about 20 metres, here was Buck Rogers made real—certainly before long engineers would work out the remaining wrinkles and everybody would be taking to the skies.

And then a funny thing happened—nothing. Wendell Moore, creator of the rocketbelt at Bell, died in 1969 at age 51, and with no follow-up interest from the U.S. Army, the project was cancelled and the Bell rocketbelt never flew again. Enter Nelson Tyler, engineer and aerial photographer, who on his own initiative built a copy of the Bell rocketbelt which, under his ownership and subsequent proprietors made numerous promotional appearances around the world, including the opening ceremony of the 1984 Olympics in Los Angeles, before a television audience estimated in excess of two billion.

All of this is prologue to the utterly bizarre story of the RB-2000 rocketbelt, launched by three partners in 1992, motivated both by their individual obsession with flying a rocketbelt and dreams of the fortune they'd make from public appearances: the owners of the Tyler rocketbelt were getting US$25,000 per flight at the time. Obsession is not a good thing to bring to a business venture, and things rapidly went from bad to worse to truly horrid. Even before the RB-2000's first and last public flight in June 1995 (which was a complete success), one of the partners had held a gun to another's head who, in return, assaulted the first with a hammer, inflicting serious wounds. In July of 1998, the third partner was brutally murdered in his home, and to this day no charges have been made in the case. Not long thereafter one of the two surviving partners sued the other and won a judgement in excess of US$10 million and custody of the RB-2000, which had disappeared immediately after its sole public flight. When no rocketbelt or money was forthcoming, the plaintiff kidnapped the defendant and imprisoned him in a wooden box for eight days, when fortuitous circumstances permitted the victim to escape. The kidnapper was quickly apprehended and subsequently sentenced to life plus ten years for the crime (the sentence was later reduced to eight years). The kidnappee later spent more than five months in jail for contempt of court for failing to produce the RB-2000 in a civil suit. To this day, the whereabouts of the RB-2000, if it still exists, are unknown.

Now, you don't need to be a rocket scientist to figure out that flitting through the sky with a contraption powered by highly volatile and corrosive propellant, with total flight time of 21 seconds, and no backup systems of any kind is a perilous undertaking. But who would have guessed that trying to do so would entail the kinds of consequences the RB-2000 venture inflicted upon its principals?

A final chapter covers recent events in rocketbelt land, including the first International Rocketbelt Convention in 2006. The reader is directed to Peter Gijsberts' www.rocketbelt.nl site for news and additional information on present-day rocketbelt projects, including commercial ventures attempting to bring rocketbelts to market. One of the most remarkable things about the curious history of rocketbelts is that, despite occasional claims and ambitious plans, in the more than 45 years which have elapsed since the first flight of the Bell rocketbelt, nobody has substantially improved upon its performance.

A U.S. Edition was published in 2005, but is now out of print.

Posted at 15:06 Permalink

Thursday, December 20, 2007

Reading List: Energy Victory

Zubrin, Robert Energy Victory. Amherst, NY: Prometheus Books, 2007. ISBN 1-59102-591-5.
This is a tremendous book—jam-packed with nerdy data of every kind. The author presents a strategy aiming for the total replacement of petroleum as a liquid fuel and chemical feedstock with an explicit goal of breaking the back of OPEC and, as he says, rendering the Middle East's near-monopoly on oil as significant on the world economic stage as its near-monopoly on camel milk.

The central policy recommendation is a U.S. mandate that all new vehicles sold in the U.S. be “flex-fuel” capable: able to run on gasoline, ethanol, or methanol in any mix whatsoever. This is a proven technology; there are more than 6 million gasoline/ethanol vehicles on the road at present, more than five times the number of gasoline/electric hybrids (p. 27), and the added cost over a gas-only vehicle is negligible. Gasoline/ethanol flex-fuel vehicles are approaching 100% of all new sales in Brazil (pp. 165–167), and that without a government mandate. Present flex vehicles are either gasoline/ethanol or gasoline/methanol, not tri-fuel, but according to Zubrin that's just a matter of tweaking the exhaust gas sensor and reprogramming the electronic fuel injection computer.

Zubrin argues that methanol capability in addition to ethanol is essential because methanol can be made from coal or natural gas, which the U.S. has in abundance, and it enables utilisation of natural gas which is presently flared due to being uneconomical to bring to market in gaseous form. This means that it isn't necessary to wait for a biomass ethanol economy to come on line. Besides, even if you do produce ethanol from, say, maize, you can still convert the cellulose “waste” into methanol economically. You can also react methanol into dimethyl ether, an excellent diesel fuel that burns cleaner than petroleum-based diesel. Coal-based methanol production produces greenhouse gases, but less than burning the coal to make electricity, then distributing it and using it in plug-in hybrids, given the efficiencies along the generation and transmission chain.

With full-flex, the driver becomes a genuine market player: you simply fill up from whatever pump has the cheapest fuel among those available wherever you happen to be: the car will run fine on any mix you end up with in the tank. People in Brazil have been doing this for the last several years, and have been profiting from their flex-fuel vehicles now that domestic ethanol is cheaper than gasoline. Brazil, in fact, reduced its net petroleum imports to zero in 2005 (from 80% in 1974), and is now a net exporter of energy (p. 168), rendering the Brazilian economy entirely immune to the direct effects of OPEC price shocks.

Zubrin also demolishes the argument that ethanol is energy neutral or a sink: recent research indicates that corn ethanol multiplies the energy input by a factor between 6 and 20. Did you know that of the two authors of an oft-cited 2005 “ethanol energy sink” paper, one (David Pimentel) is a radical Malthusian who wants to reduce the world population by a factor of three and the other (Tadeusz Patzek) comes out of the “all bidness” (pp. 126–135)?

The geopolitical implications of energy dependence and independence are illustrated with examples from both world wars and the present era, and a hopeful picture sketched in which the world transitions from looting developed countries to fill the coffers of terror masters and kleptocrats to a future where the funds for the world's liquid fuel energy needs flow instead to farmers in the developing world who create sustainable, greenhouse-neutral fuel by their own labour and intellect, rather than pumping expendable resources from underground.

Here we have an optimistic, pragmatic, and open-ended view of the human prospect. The post-petroleum era could be launched on a global scale by a single act of the U.S. Congress which would cost U.S. taxpayers nothing and have negligible drag on the domestic or world economy. The technologies required date mostly from the 19th century and are entirely mature today, and the global future advocated has already been prototyped in a large, economically and socially diverse country, with stunning success. Perhaps people in the second half of the 21st century will regard present-day prophets of “peak oil” and “global warming” as quaint as the doomsayers who foresaw the end of civilisation when firewood supplies were exhausted, just years before coal mines began to fuel the industrial revolution.

Posted at 19:13 Permalink

Tuesday, December 18, 2007

Reading List: Fashion Babylon

Edwards-Jones, Imogen. Fashion Babylon. London: Corgi Books, 2006. ISBN 0-552-15443-1.
This is a hard-to-classify but interesting and enjoyable book. I'm not sure even whether to call it fiction or nonfiction: the author has invented a notional co-author, “Anonymous”, who relates, condensed into a single six-month fashion season, anecdotes from a large collection of sources within the British fashion industry, all of which the author vouches for as authentic. Celebrities appear under their own names, and the stories involving them (often bizarre) are claimed to be genuine.

If you're looking for snark, cynicism, cocaine, cigarettes, champagne, anorexia, and other decadence and dissipation, you'll find it, but you'll also take away a thorough grounding in the economics of a business fully as bizarre as the software industry. The gross margin is almost as high and, except for the brand name and associated logos, there is essentially zero protection of intellectual property (as long as you don't counterfeit the brand, you can knock-off any design, just as you can create a work-alike for almost any non-patent-protected software product and sell it for a tiny fraction of the price of the prototype). The vertiginous plunge from the gross margin to the meagre bottom line is mostly promotional hype: blow-outs to “build the brand”. So it may increasingly become in the software business as increases in functionality in products appeal to a smaller and smaller fraction of the customer base, or even reduce usability (Windows Vista, anybody?).

A U.S. Edition will be published in February 2008.

Posted at 23:53 Permalink

Friday, December 14, 2007

Notes toward a General Theory of Paranormal Phenomena Posted

Notes toward a General Theory of Paranormal Phenomena expounds an idea that's been evolving in my mind since the 1990s. The document has been a work in progress since 2006: linked to from various places deep within the site and from the occasional posting in this chronicle, but not deemed ready for a top-level listing in the navigation tree. I've finally decided that, with some revisions and additions, it's converged reasonably well toward my take on the topic. In any case, I can't think of anything to add to the document in its present state which would make it more comprehensive or comprehensible. So, as with innumerable software projects and a recent history book, it's time to exclaim “Ship it!” and loose it upon the world, reflexively cringing in anticipation of the response from the relentlessly (and admirably) rational and punctilious audience who frequent this site.

In this edition I've added an item to the “Applications” section which describes how placebos, homeopathy, and faith healing might work within this “multiverse navigation” model.

Posted at 22:10 Permalink

Monday, December 10, 2007

Reading List: Whoosh Boom Splat

Gurstelle, William. Whoosh Boom Splat. New York: Three Rivers Press, 2007. ISBN 0-307-33948-3.
So you've read The Dangerous Book for Boys and now you're wondering, “Where's the dangerous book for adults?”. Well, here you go. Subtitled “The Garage Warrior's Guide to Building Projectile Shooters”, in just 160 pages with abundant illustrations, the author shows how with inexpensive materials, handyman tools, and only the most modest of tinkering skills, you can build devices including a potato cannon which can shoot a spud more than 200 metres powered by hairspray, a no-moving-parts pulse jet built from a mason jar and pipe fittings, a steam cannon, a “snap shooter” made from an ordinary spring-type wooden clothespin which can launch small objects across a room (or, should that not be deemed dangerous enough, flaming matches [outside, please!]), and more. The detailed instructions for building the devices and safety tips for operating them are accompanied by historical anecdotes and background on the science behind the gadgets. Ever-versatile PVC pipe is used in many of the projects, and no welding or metalworking skills (beyond drilling holes) are required.

If you find these projects still lacking that certain frisson, you might want to check out the author's Adventures from the Technology Underground, which you can think of as The Absurdly Dangerous Book for Darwin Award Candidates, albeit without the detailed construction plans of the present volume. Enough scribbling—time to get back to work on that rail gun.

Posted at 21:22 Permalink

Saturday, December 8, 2007

Reading List: Dark Mission

Hoagland, Richard C. and Mike Bara. Dark Mission. Los Angeles: Feral House, 2007. ISBN 1-932595-26-0.
Author Richard C. Hoagland first came to prominence as an “independent researcher” and advocate that “the face on Mars” was an artificially-constructed monument built by an ancient extraterrestrial civilisation. Hoagland has established himself as one of the most indefatigable and imaginative pseudoscientific crackpots on the contemporary scene, and this œuvre pulls it all together into a side-splittingly zany compendium of conspiracy theories, wacky physics, imaginative image interpretation, and feuds within the “anomalist” community—a tempest in a crackpot, if you like.

Hoagland seems to possess a visual system which endows him with a preternatural ability, undoubtedly valuable for an anomalist, of seeing things that aren't there. Now you may look at a print of a picture taken on the lunar surface by an astronaut with a Hasselblad camera and see, in the black lunar sky, negative scratches, film smudges, lens flare, and, in contrast-stretched and otherwise manipulated digitally scanned images, artefacts of the image processing filters applied, but Hoagland immediately perceives “multiple layers of breathtaking ‘structural construction’ embedded in the NASA frame; multiple surviving ‘cell-like rooms,’ three-dimensional ‘cross-bracing,’ angled ‘stringers,’ etc… all following logical structural patterns for a massive work of shattered, but once coherent, glass-like mega-engineering” (p. 153, emphasis in the original). You can see these wonders for yourself on Hoagland's site, The Enterprise Mission. From other Apollo images Hoagland has come to believe that much of the near side of the Moon is covered by the ruins of glass and titanium domes, some which still reach kilometres into the lunar sky and towered over some of the Apollo landing sites.

Now, you might ask, why did the Apollo astronauts not remark upon these prodigies, either while presumably dodging them when landing and flying back to orbit, nor on the surface, nor afterward. Well, you see, they must have been sworn to secrecy at the time and later (p. 176) hypnotised to cause them to forget the obvious evidence of a super-civilisation they were tripping over on the lunar surface. Yeah, that'll work.

Now, Occam's razor advises us not to unnecessarily multiply assumptions when formulating our hypotheses. On the one hand, we have the mainstream view that NASA missions have honestly reported the data they obtained to the public, and that these data, to date, include no evidence (apart from the ambiguous Viking biology tests on Mars) for extraterrestrial life nor artefacts of another civilisation. On the other, Hoagland argues:

  • NASA has been, from inception, ruled by three contending secret societies, all of which trace their roots to the gods of ancient Egypt: the Freemasons, unrepentant Nazi SS, and occult disciples of Aleister Crowley.
  • These cults have arranged key NASA mission events to occur at “ritual” times, locations, and celestial alignments. The Apollo 16 lunar landing was delayed due to a faked problem with the SPS engine so as to occur on Hitler's birthday.
  • John F. Kennedy was assassinated by a conspiracy including Lyndon Johnson and Congressman Albert Thomas of Texas because Kennedy was about to endorse a joint Moon mission with the Soviets, revealing to them the occult reasons behind the Apollo project.
  • There are two factions within NASA: the “owls”, who want to hide the evidence from the public, and the “roosters”, who are trying to get it out by covert data releases and cleverly coded clues.

    But wait, there's more!

  • The energy of the Sun comes, at least in part, from a “hyperdimensional plane” which couples to rotating objects through gravitational torsion (you knew that was going to come in sooner or later!) This energy expresses itself through a tetrahedral geometry, and explains, among other mysteries, the Great Red Spot of Jupiter, the Great Dark Spot of Neptune, Olympus Mons on Mars, Mauna Kea in Hawaii, and the precession of isolated pulsars.
  • The secrets of this hyperdimensional physics, glimpsed by James Clerk Maxwell in his quaternion (check off another crackpot checklist item) formulation of classical electrodynamics, were found by Hoagland to be encoded in the geometry of the “monuments” of Cydonia on Mars.
  • Mars was once the moon of a “Planet V”, which exploded (p. 362).

    And that's not all!

  • NASA's Mars rover Opportunity imaged a fossil in a Martian rock and then promptly ground it to dust.
  • The terrain surrounding the rover Spirit is littered with artificial objects.
  • Mars Pathfinder imaged a Sphinx on Mars.

    And if that weren't enough!

  • Apollo 17 astronauts photographed the head of an anthropomorphic robot resembling C-3PO lying in Shorty Crater on the Moon (p. 487).

It's like Velikovsky meets The Illuminatus! Trilogy, with some of the darker themes of “Millennium” thrown in for good measure.

Now, I'm sure, as always happens when I post a review like this, the usual suspects are going to write to demand whatever possessed me to read something like this and/or berate me for giving publicity to such hyperdimensional hogwash. Lighten up! I read for enjoyment, and to anybody with a grounding in the Actual Universe™, this stuff is absolutely hilarious: there's a chortle every few pages and a hearty guffaw or two in each chapter. The authors actually write quite well: this is not your usual semi-literate crank-case sludge, although like many on the far fringes of rationality they seem to be unduly challenged by the humble apostrophe. Hoagland is inordinately fond of the word “infamous”, but this becomes rather charming after the first hundred or so, kind of like the verbal tics of your crazy uncle, who Hoagland rather resembles. It's particularly amusing to read the accounts of Hoagland's assorted fallings out and feuds with other “anomalists”; when Tom Van Flandern concludes you're a kook, then you know you're out there, and I don't mean hanging with the truth.

Posted at 23:31 Permalink

Tuesday, December 4, 2007

Reading List: The Ghost Map

Johnson, Steven. The Ghost Map. New York: Riverhead Books, 2006. ISBN 1-59448-925-4.
From the dawn of human civilisation until sometime in the nineteenth century, cities were net population sinks—the increased mortality from infectious diseases, compounded by the unsanitary conditions, impure water, and food transported from the hinterland and stored without refrigeration so shortened the lives of city-dwellers (except for the ruling class and the wealthy, a small fraction of the population) that a city's population was maintained only by a constant net migration to it from the countryside. In densely-packed cities, not only does an infected individual come into contact with many more potential victims than in a rural environment, highly virulent strains of infectious agents which would “burn out” due to rapidly killing their hosts in farm country or a small village can prosper in a city, since each infected host still has the opportunity to infect many others before succumbing. Cities can be thought of as Petri dishes for evolving killer microbes.

No civic culture medium was as hospitable to pathogens as London in the middle of the 19th century. Its population, 2.4 million in 1851, had exploded from just one million at the start of the century, and all of these people had been accommodated in a sprawling metropolis almost devoid of what we would consider a public health infrastructure. Sewers, where they existed, were often open and simply dumped into the Thames, whence other Londoners drew their drinking water, downstream. Other residences dumped human waste in cesspools, emptied occasionally (or maybe not) by “night-soil men”. Imperial London was a smelly, and a deadly place. Observing it first-hand is what motivated Friedrich Engels to document and deplore The Condition of the Working Class in England.

Among the diseases which cut down inhabitants of cities, one of the most feared was cholera. In 1849, an outbreak killed 14,137 in London, and nobody knew when or where it might strike next. The prevailing theory of disease at this epoch was that infection was caused by and spread through “miasma”: contaminated air. Given how London stank and how deadly it was to its inhabitants, this would have seemed perfectly plausible to people living before the germ theory of disease was propounded. Edwin Chadwick, head of the General Board of Health in London at the epoch, went so far as to assert (p. 114) “all smell is disease”. Chadwick was, in many ways, one of the first advocates and implementers of what we have come to call “big government”—that the state should take an active role in addressing social problems and providing infrastructure for public health. Relying upon the accepted “miasma” theory and empowered by an act of Parliament, he spent the 1840s trying to eliminate the stink of the cesspools by connecting them to sewers which drained their offal into the Thames. Chadwick was, by doing so, to provide one of the first demonstrations of that universal concomitant of big government, unintended consequences: “The first defining act of a modern, centralized public-health authority was to poison an entire urban population.” (p. 120).

When, in 1854, a singularly virulent outbreak of cholera struck the Soho district of London, physician and pioneer in anæsthesia John Snow found himself at the fulcrum of a revolution in science and public health toward which he had been working for years. Based upon his studies of the 1849 cholera outbreak, Snow had become convinced that the pathogen spread through contamination of water supplies by the excrement of infected individuals. He had published a monograph laying out this theory in 1849, but it swayed few readers from the prevailing miasma theory. He was continuing to document the case when cholera exploded in his own neighbourhood. Snow's mind was not only prepared to consider a waterborne infection vector, he was also one of the pioneers of the emerging science of epidemiology: he was a founding member of the London Epidemiological Society in 1850. Snow's real-time analysis of the epidemic caused him to believe that the vector of infection was contaminated water from the Broad Street pump, and his persuasive presentation of the evidence to the Board of Governors of St. James Parish caused them to remove the handle from that pump, after which the contagion abated. (As the author explains, the outbreak was already declining at the time, and in all probability the water from the Broad Street pump was no longer contaminated then. However, due to subsequent events and discoveries made later, had the handle not been removed there would have likely been a second wave of the epidemic, with casualties comparable to the first.)

Afterward, Snow, with the assistance of initially-sceptical clergyman Henry Whitehead, whose intimate knowledge of the neighbourhood and its residents allowed compiling the data which not only confirmed Snow's hypothesis but identified what modern epidemiologists would call the “index case” and “vector of contagion”, revised his monograph to cover the 1854 outbreak, illustrated by a map which illustrated its casualties that has become a classic of on-the-ground epidemiology and the graphical presentation of data. Most brilliant was Snow's use (and apparent independent invention) of a Voronoi diagram to show the boundary, by streets, of the distance, not in Euclidean space, but by walking time, of the area closer to the Broad Street pump than to others in the neighbourhood. (Oddly, the complete map with this crucial detail does not appear in the book: only a blow-up of the central section without the boundary. The full map is here; depending on your browser, you may have to click on the map image to display it at full resolution. The dotted and dashed line is the Voronoi cell enclosing the Broad Street pump.)

In the following years, London embarked upon a massive program to build underground sewers to transport the waste of its millions of residents downstream to the tidal zone of the Thames and later, directly to the sea. There would be one more cholera outbreak in London in 1866—in an area not yet connected to the new sewers and water treatment systems. Afterward, there has not been a single epidemic of cholera in London. Other cities in the developed world learned this lesson and built the infrastructure to provide their residents clean water. In the developing world, cholera continues to take its toll: in the 1990s an outbreak in South America infected more than a million people and killed almost 10,000. Fortunately, administration of rehydration therapy (with electrolytes) has drastically reduced the likelihood of death from a cholera infection. Still, you have to wonder why, in a world where billions of people lack access to clean water and third world mega-cities are drawing millions to live in conditions not unlike London in the 1850s, that some believe that laptop computers are the top priority for children growing up there.

A paperback edition is now available.

Posted at 23:51 Permalink

Monday, December 3, 2007

Earth and Moon Viewer, Your Sky, and Solar System Live Updated

I have just posted updated versions of Earth and Moon Viewer, Your Sky, and Solar System Live which improve usability by wrapping applicable radio button and checkbox controls in XHTML “<label>” containers. This is an often-neglected refinement which makes a page both kinder to visitors and more professional in appearance. When you're creating an XHTML form with controls of these types, if you simply include the controls with adjacent labels, the user has to click on the button itself (which in these cases is rather small), but if you enclose the control and its legend within a “<label>” container (or, equivalently, tie the legend to the control with the “<label for="id">” form of the tag), then the user can click anywhere in the legend as well as on the control itself. This not only provides a larger target, it's consistent with the behaviour of most window systems with which users are familiar.

For example, consider the following do-nothing form:

Note that you can click on either the button or the legend of “Gromify”, which is enclosed in a “<label>” container, but only on the button for “Brozzulate”, which is not.

The weasel word “applicable” in the first sentence excludes legends of buttons which are already links to a help file item explaining the button. Obviously, a legend can only do one thing when you click it, and I decided that preserving help file links was more important than the convenience of pressing the button by clicking the legend. The ability to click on legends has been extended not only to dynamic pages returned by the applications, but to all associated static pages (custom request forms, help text, etc.).

A few additional changes were made in Your Sky:

Posted at 21:19 Permalink