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Dr. John SNow & the BRoad Street Pump



Today we know that tiny microbes carried in water can cause all sorts of diseases. However, the connection between germs and illness was not always recognised. In fact, before the mid 1800s, diseases were thought to be caused by stale or ‘bad’ air known as miasma. There was little understanding about how microscopic life could affect humans. In 1861, things changed. With the presentation of the ‘germ theory of disease,’ microscopic organisms were finally identified as the cause of many diseases. In 1854 a cholera outbreak in London was studied and analysed by the British physician Dr John Snow. By plotting the location of cases, Snow was able to discover that the cluster of cases seemed to suggest an association with water and not ‘disease causing’ air, as most people believed.

Water's Deadly Connection

In this activity, you will model Show's strategy as you plot and analyze the location of victims of a mysterious epidemic.


  1. Examine the map on the next page. Note how an overlay of the grid lines divides the map into 49 square regions. Each of these regions is identified by a letter (horizontal row) and a number value (vertical column).
  2. Examine the table that illustrates the location of the cholera victims. Note how each of the locations matches a square on the map grid.
  3. For each of the 56 victims, drag a mark in the appropriate map box.
  4. Once you have marked up the map, it’s time to analyze the visual layout or your data.

Can you do the same type of investigative work?

Drag an X to mark each location as complete

Drag a dot to mark each location on the map

Use the locations below to mark the map with dots. Drag the X's to cross off each location on the list as you go. The first location has been done for you!

Finish Up