# Gall's Stereographic

## Description

Gall's stereographic was designed around 1855. It is a cylindrical projection with two standard parallels at latitudes 45° N and S.

## Projection method

A cylindrical stereographic projection based on two standard parallels at 45° N and S. The globe is projected perspectively onto a secant cylinder from the point on the equator opposite a given meridian. Meridians are equally spaced straight lines. Parallels are straight lines with spacing increasing away from the equator. Poles are straight lines.

## Lines of contact

Two lines at 45° N and S.

## Linear graticules

All meridians and parallels.

## Properties

### Shape

Shapes are true at latitudes 45° N and S. Distortion slowly increases away from these latitudes and becomes severe at the poles.

### Area

Area is true at latitudes 45° N and S. Distortion slowly increases away from these latitudes and becomes severe at the poles.

### Direction

Locally correct at latitudes 45° N and S. Generally distorted elsewhere.

### Distance

Scale is true in all directions along latitudes 45° N and S. Scale is constant along parallels and is symmetrical around the equator. Distances are compressed between latitudes 45° N and S and expanded beyond them.

## Limitations

Used only for world maps.

## Uses and applications

Used for world maps in British atlases.

## Parameters

### Desktop

- False Easting
- False Northing
- Central Meridian

Supported on spheres only.

geographic_coordinate_systems.pdf | A geographic coordinate systems pdf file which contains lists of supported gcs and vcs. |

projected_coordinate_systems.pdf | A projected coordinate systems pdf file which contains lists of supported pcs. |

geographic_transformations.pdf | A geographic transformations pdf file which contains lists of supported geographic and vertical transformations. |

### Workstation

- Longitude of Central Meridian

Supported on spheres only.

geographic_coordinate_systems.pdf | A geographic coordinate systems pdf file which contains lists of supported gcs and vcs. |

projected_coordinate_systems.pdf | A projected coordinate systems pdf file which contains lists of supported pcs. |

geographic_transformations.pdf | A geographic transformations pdf file which contains lists of supported geographic and vertical transformations. |