WHAT LIT THE GREAT FIRE OF CHICAGO: COW OR COMET? The city of Chicago was ravaged by a fire that broke out around 9 p.m. on the night of 8 October 1871. It ranks high on the list of urban conflagrations in the history of the United States: by the time the fire was on the wane nearly four square miles of the city had been razed to the ground, leaving up to 300 dead, over 100,000 homeless and a clean-up bill of $222 million, approximately $4.5 billion in today''s money. Even before the embers had cooled, rumours were blaming the conflagration on the O''Leary family of DeKoven Street, claiming that the fire had been started in a barn to the rear of that property when a drunken Catherine O''Leary''s ineptitude at the milking of her cow had caused the belligerent bovine to kick over a lamp she had carelessly left on the straw-strewn floor. No matter the early refutations of this maliciously inspired nonsense, the notion of a simple cow bringing down the city of Chicago gripped the collective imagination, with Brian Wilson writing his ''Mrs O''Leary''s Cow'' track for the Beach Boys'' initially unreleased Smile album as recently as 1967. One of the first fire outbreaks attended to that night was indeed at a barn to the rear of the O''Leary residence at 137 DeKoven Street.

The fire marshal in attendance later testified: ''We got the fire under control and it would not have gone a foot further but the next thing I knew was that they came and told me that St Paul''s Church, about two squares north, was on fire.'' The team rushed to attend that event but, as that same fire marshal recalled, on arrival, ''The next thing I knew then was that the fire was over at Bateham''s Planing Mill . buildings far beyond the line of fire, and in no contact with it, burst into flames from the interior''. If nothing else, this fire marshal''s testimony makes clear that the old legend of the disaster having been started by Catherine O''Leary''s cow kicking over her lamp can be safely dismissed, especially as the journalist who first published the story would later have to admit to its invention. The Irish Catholic contingent of Chicago was not held in high regard by the Protestant elite so a scapegoat, or perhaps a scapecow, from that community fitted the bill nicely. With history books very much focused on the Great Fire of Chicago, there was often little mention of the fact that this was not the only fire in the area of the American Great Lakes that night. The townships of Port Huron and White Rock, both at the southern end of Lake Huron, were pretty much wiped out the same night, as were those of Holland and Manistee on Lake Michigan. Across the lake from Manistee and Holland was the site of a fire so massive that it dwarfed all the others put together; the largely forgotten fire of Peshtigo, which killed around 2,500 people and destroyed a dozen surrounding villages and over 1.

5 million fake history acres of woodland. It was unquestionably the worst fire in American history - so how did all this get overshadowed by the Chicago fire? At its peak, the Peshtigo fire presented the awesome sight of a towering wall of flame across a 5-mile front with temperatures exceeding 2,000°F, reaching speeds of over 100 mph. Trains were melted where they stood while buildings and their fleeing occupants were burned before the fire had even reached them. As was the case across the waters in Chicago, the Peshtigo event was marked by multiple and diverse fires which, erupting at random across a wide area, left the people at a loss as to the direction in which to flee. Many who sought sanctuary in the nearby rivers and lakes either drowned or died of hypothermia. The subsequent study of the fire, its prevailing conditions and the fire tornados it created produced what is still known as the Peshtigo Paradigm. A blueprint for how to reproduce the holocaustic conditions that wiped out Peshtigo, this study was used by the US Air Force and British Bomber Command to generate the fire storms in their Second World War incendiary bombing of Dresden and Tokyo, which inflicted death tolls to dwarf those of Hiroshima and Nagasaki combined. The most intriguing aspect presented by this collection of fires is the fact that, when viewed from the air or plotted on a map, they present a spread pattern similar to a shotgun blast to a solid surface from a shallow angle.

This led some to consider a culprit far more mysterious than Mother O''Leary''s cow - the blistering hot debris falling from Biela''s Comet, which also broke up over the area that night. First mooted in 1883, the comet theory was roundly dismissed, mainly because the man who put forward the theory was Ignatius Loyola Donnelly, a US congressman and amateur scientist widely perceived, with some justification, as a bit of a crank. In Donnelly''s favour were the countless witness reports of balls of fire falling from the sky that night and spontaneous groundlevel ignitions of blue flame, which Donnelly maintained were consistent with methane found in comets and comet debris. More recently, the American physicist Dr Robert Wood took up Donnelley''s long-abandoned gauntlet and, in 2004, presented his conclusions to the American Institute of Aeronautics and Astronautics, asserting that there was, after all, much to support the notion that this cluster of fires had indeed been started by Biela''s break-up showering the area with white-hot debris as this - and only this - squared with what so many eyewitnesses uniformly recalled at the time. Soon after the fires came the publication of The History of the Great Conflagration (1871) by John Washington Sheahan and George Putnam Upton, two local historians who collected and meticulously logged locals'' accounts of the night. They reported recollections of what happened in a village near Peshtigo: But a few minutes after nine o''clock, and by a singular coincidence precisely the time at which the Chicago fire commenced, the people of the village heard a terrible roar. It was that of a tornado crashing through the forests. Instantly the heavens were illuminated with a terrible glare.

The sky, which had been so dark a moment before, burst into clouds of flame. A spectator of the terrible events said the fire did not come upon them gradually from burning trees and other objects to the windward, but from a whirlwind of flames in great clouds from above the tops of the trees. Others were equally adamant that the fire came ''in great sheeted flames from the heavens'' and also spoke of ''a pitiless rain of fire and hot sand from the skies''. Many also spoke of ''great balls of fire falling from the sky. The whole sky was filled with them, great smoky masses about the size of a large balloon and travelling at unbelievable speed. They fell to the ground and burst.'' As to those mentions of searing hot sand, this was addressed in the book Mrs O''Leary''s Comet (1985) by Mel Waskin, head writer and science producer for the Chicago-based Coronet Educational Films. Knowing that meteors can bring in their wake showers of silica, Waskin observed: ''There was sand on the beaches but the beaches lay to the east and the wind was blowing from the west and the south.

There was no sand on the floor of the forests nor on the farmlands of Wisconsin.'' It is true that, in the main, debris from space is usually cold by the time it hits earth, and that many such visitors from space of modest size are destroyed by their passage through the earth''s atmosphere, resulting in them falling as ''sand''. Other larger ones, however, have in the past and more recently made it through that barrier to inflict significant earth-impact with accompanying fires. On 29 August 2011 a single such object was observed leaving a flaming trail as it passed over the Peruvian city of Cusco to crash into the tinder-dry forests to the south of the city, immediately bursting into flames. Much the same happened on 11 August 2013 in the forests adjacent to the town of Kepez Çanakkale in Turkey. In a major event, such as the disintegration of Beila''s Comet, hundreds or even thousands of individual pieces of varying size would have resulted, some burning up to fall as the much-cited hot sand at Peshtigo while larger ones made it to earth to start fires. In 1893, the journalist Michael Ahern finally admitted his libel of the O''Learys'' cow but by then no one was listening. At least Mrs O''Leary and her cow finally received official exoneration from the Chicago City Council which, in October 1997, held a somewhat belated and rather tongue-in-cheek ceremony.

The cow, it was proclaimed, had been the victim of bad press.