Calibration slide, England finder slide, S7 (EMS)

S7 is a 75mm x 26mm (3x1) "glass slide marked above the top surface so that a referenced position can be read directly relative to the locating edges.  That means it's marked at 1 mm intervals with a square grid. Each square contains a centre ring bearing reference letters and numbers, subdividing the rest of the square into four segments numbered 1 to 4.

Reference numbers run horizontally from 1 to 75 and letters vertically from A to Z (omitting I) The main edge of the position is the bottom of the slide used in combination with either the slide's left or right vertical rim.

The aim of the finder is to provide the microscopist with a simple way to record the location of a particular field of interest, so that another person may move to another laboratory at a later date, or the same position or use any other England Finder on any other microscope.

All England Finders that have been produced over 40 years are the same. 

The location for all England Finder slides is the same. Label a tag on the left side of the slide of the sample, showing the way to repeat. By replacing the specimen slide with England Finder, you can notice a feature of interest by taking care not to disturb the position.

The feature can also be re-located at another place or time by reversing the procedure. A total of 100 positions on a slide can be accurately located.