Glossary
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Sonar Images of
the Site of the P.S. Lady Sherbrooke
In order to further investigate the possibility that there was a treasure under the surface of the Saint-Lawrence River a series of sonar images were produced of the area believed to hold the mystery. In June 1983, with the assistance of the CHASQ team, Dr. Harold E. Edgerton and Peter Mui from M.I.T. produced electronically imaged a section of the riverbed. The basic rationale of a sonar is to map the topography of the riverbed. The first tool used, and seen here, is a side scanner. It is towed behind a moving boat as the boat passes over the area of investigation.
The image produced (below, left) shows a wide area. Any potential areas of interest are then further examined with a subbottom profiler. This second apparatus produces a different, and more precise image (below, right). Any dense objects appear as dark sections. When a possible area of interest appears a diver can explore to see if the object is indeed worth further exploration.
It was on the final day, of a week of sonar mapping, that the team found the site it believed what a steam ship from the John Molson Line. History shows that they were indeed correct.
