The Museum is on a mission to digitise 80 million specimens. We want to mobilise the collections to give the global community access to this unrivaled historical, cultural, geographical and taxonomic resource.
Carrying out pilot projects helps us to establish bespoke digital capture workflows on areas of the collections. Mercers Trust funded a small scale pilot project to digitise the more difficult to image herbarium specimens from the Samuel Browne Volumes of the Sloane Herbarium that contain specimens of medicinal plants form India. Dr Steen Dupont from the Museum’s Digital Collection programme has been leading on this project.
The Sir Hans Sloane Herbarium
Sloane’s collections are the founding core of the Museum’s collections and occupy a central position in its (and the British Museum’s) history. Over 300+ years since his death his natural history collections have had mixed fortunes, with many mammal, bird and reptile specimens being lost or destroyed.
His plant collections survived and are still housed in the Museum today. Some of this has been digitised by the Museum using a large-format camera with a digital scanner attachment. However, some volumes were completely unsuitable for this technique and require a different approach.
Specimen imaging presented the main challenge for this project. The very restricted opening of the herbarium volumes does not allow for conventional book scanners or static cameras to achieve optimal imaging angles of the individual pages. We therefore needed some new innovative hardware to tackle this challenge.
Assessment and Conservation
Museum paper conservators assessed two of the most tightly bound volumes and established 12 pages that were representative of specimens throughout the volume. Curators then carried out essential conservation of these pages prior to imaging. The pages and specimens needed to be cleaned and some paper repairs of small tears around the edges of pages were necessary.
To allow for variation in drape of the pages, the imaging camera was placed on an adjustable support arm allowing the camera to be placed as parallel to the page being imaged as possible. This helps to reduce the page skew in the photograph and to produce a more accurate digital representation of the specimens.
Adjustable book cradle
One of the main aspects restricting a book’s opening is the flexibility of the spine. Herbarium books are made of materials that make the spines inherently rigid. To compensate for the spine stiffness, a new book cradle was designed and built in house for this project.
The cradle has free spine support which allows the independent movement of the spine and increased book opening without applying any external pressures. The newly designed book cradle was also positioned on a turntable to make it possible to rotate the book to image the opposite page without handling the fragile volume more than necessary.
Using Lego to design new page clamps
The age of the book and the presence of stiff botanical material on the pages results in pages that do not drape or stay open easily. We looked into commonly used page restraining tools such as polyethylene bands and lead weighted strings; however these were not suitable for pages that have very variable specimens on them that can extend right to the edge of some of the pages.
The solution was to emulate force and directional friction of a human hand by designing collapsible crescent shaped page clamps that could rest on the variable positions on the imaged page while generating a downward pressure and outward pull.
This isn’t the first time that the Museum has used Lego as a solution to solve a digitisation problem. In 2015, Dr Steen Dupont and colleagues used Lego to create an affordable and reliable pinned insect manipulator.
‘By making it completely out of Lego it is possible to have it ordered and shipped to almost anywhere, and the low cost makes it affordable to everyone. It is especially important for scientists in developing countries and students.’
Herbarium Imaging Equipment (HerbIE)
During the pilot project three distinct pieces of hardware have been designed and developed to meet the challenge of imaging herbarium books. We are drawing these three components together and Dr Steen Dupont has called this Herbarium Imaging equipment (or HerbIE for short!).
Using HerbIE we are able to capture raw images that are as accurate as possible. From here, the images will need further processing to correct skew, colour and alignment, and transcription of all the text and labels around each specimen will need to be completed.
Completing a pilot on representative pages across the two Samuel Browne volumes of the Sloane Herbarium has enabled us to understands the needs and the unique challenge of this type of collection. With future funding we will be able to use our innovative hardware to upscale this work and digitise more of the most difficult parts of this collection.
This provides a digital surrogate for a culturally irreplaceable collection and provides open access to this collection to a wider global audience online. By using affordable and replicable tools we hope that our pilot will enable and inspire others to tackle challenges of digitisation within other collections across the globe.
To stay up to date with news from the Digital Collection Programme, visit the website or follow us on Twitter. Visit the Data Portal to start making use of the parts of the Museum’s collections that have already been digitised to date.