Summary: Explanation of various methods of plotting routes across the globe.
Description: REEL ONE: Visual explanation using globe model of Equator and Greenwich Meridian line and locating places on the globe using lines of latitude and longitude. Latitude is always quoted first. Explanation of shortest distance between two points on the surface of a sphere being the shorter arc of the great circle passing through those points. Great Circle Track and Rhumb Line track explained. Cylindrical Projections explained by transposing globe onto a cylindrical map and subsequent issues of distortion/compression of landmasses.
REEL TWO: Principle of Mercator's Projection explained and demonstration of maintaining accurate shape of landmasses by stretching lines of Meridian to same same degree as parallels of latitude to maintain scale in any direction. All maps and charts used in the RAF are Mercator's Projection. Explanation of Gnomonic Projection where any straight line represents a Great Circle and comparison of a route using Mercator's and Gnomonic Projection. Conical Projection demonstrated by placing a paper cone onto globe and surface of the northern hemisphere stretched and raised onto surface of cone and explanation of scale at different points of opened cone.
REEL THREE: Explanation that on maps supplied to the RAF, distortions can, for practical purposes, be disregarded – most maps are Conical Projection while charts are Mercator's Projection.
Alternative Title:
Colour:B&W
Digitised:
Object_Number:AMY 142
Sound:Sound
Access Conditions:
Featured Period:1939-1945
Production Date:1943
Production Country: GB
Production Details: Air Ministry (Production sponsor)
Gee Films (Production company)
