Introduction
In several of our publications we give finder references to individual specimens, especially types, in order that these specimens can be re-located using any microscope. Several sorts of finder slides have been manufactured in the past 150 or so years. In the 19th century, the most common was the Maltwood Finder. Nowadays the only one that is still readily available is the England Finder, manufactured by the Graticules division of Pyser-SGI
The England Finder
A short explanation is required here as to how England Finder references have been obtained and can be reproduced, since it is not intuitive.
The accuracy of the England Finder is guaranteed relative to three of its edges: the bottom edge (when viewed with the label positioned bottom left) and the two adjacent edges – but not the top edge.
The microscopes used in all papers on this site that give England Finder references locate slides by their top and left hand edges when viewed from in front of the microscope. But since the accuracy of the top edge of the England Finder is not guaranteed, the finder had to be positioned in the microscope the wrong way round (i.e. rotated 180° horizontally) with its bottom edge furthest from the viewer and its label in the top right hand corner. This orientation ensured that the finder was located on the stage by two of its guaranteed edges: its bottom and right hand edges as viewed with the label bottom left.
The specimen slides were positioned on the microscope stage so that the labels could be read from in front of the microscope or from the right, and they were located by their top and left hand edges.
In order for the England Finder references given to work on other microscopes and with other England Finders, it must be possible to locate the finder by its bottom and right hand edges (as viewed with the label bottom left), and to locate the specimen slide by its top and left hand edges (as viewed with the labels readable from in front of the microscope or from the right).
If it is only possible to locate the England Finder by its bottom and left hand edges, then only the vertical dimension of the reference (the letter) will work, unless the specimen slide is exactly the same width as the England Finder, in which case both dimensions will be accurate!
Instructions for re-finding specimens using England Finder references
If you wish to relocate a specimen from an English Finder reference, follow these steps:
- Place the finder slide in your microscope and position it at the reference given (pay particular attention to the orientation of the slide – see above);
- Without moving the stage, replace the finder slide with the type slide (check correct orientation);
- Focus on the slide using a low-magnification objective (e.g. x25);
- If the individual type page gives a low-magnification context shot (with the specimen indicated by an arrow), use that to help relocate the specimen.
Back to all types page.