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The earliest spot map of all

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 figure 3) [12].  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.

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." [13]  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." [13] 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." [12]  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.