Seal Dating Tool

Introduction

Welcome to the experimental seal dating tool! I built this tool in March 2023 while investigating the feasibility of using existing archival seal catalogues to create an automated system to assist cataloguers dating medieval seal matrices.

How to use this tool

Enter the size, shape and class of the seal in the filter panel and click Submit. The tool will return a predicted date, a distribution graph, and similar seal impressions that may resemble the matrix you are trying to date.

Can I use this in my research?

This tool is experimental. Use with caution and check periodically for updates and improvements.

How does it work?

The tool uses a decision tree trained on data from DIGISIG. It situates your seal in a group of similar seals and returns the typical date for that group. For further information about the training data, please visit this page.

How do I evaluate the prediction?

Start by looking at the graph. The predicted date is the typical date of the group, but each group spans a range. The shape of the graph shows how likely it is that your seal is earlier or later than the predicted date.

In Result Details below you can inspect the decision path, and up to ten similar seals drawn from the prediction group that match the shape and class you submitted.