Whilst cataloging some of the large collection of microscope slides in the herbarium I came across some slides with intriguing labels. One was labelled ‘The Moon”, another “Nelson Meditating His Prayer before the Battle of Trafalgar” and another “£20 Bank Note” – not the kind of thing we normally come across in the botany stores. I immediately set about viewing the slides under a microscope and was amazed to actually pictures of Nelson, the moon and a bank note. In the corner of the slides was the initial J.B.D.
After a few minutes on Google, I discovered that these slides were made by the 19th Century Manchester instrument maker and inventor of microphotography, John Benjamin Dancer. Dancer’s first example of microphotography was produced in 1839 and they soon became popular with microscopists.
“Dancer did not have any mass production method for turning out his micro-photograph slides and though it must have been very time consuming he is reported as having made many thousands. The method employed was explained by Mr.J.F.Stirling writing in Watsons Microscope Record No.45, Oct.1938, p.16. A glass negative of the photograph to be reduced was placed in a lantern illuminated by a flame. The image of the photograph was projected through a microscope objective mounted horizontally on to the sensitized collodion film supported on a glass sheet. Dancer speeded up production slightly by duplicating the contraption with two lanterns placed back to back with one illuminating flame in the space between the two lanterns, the whole assembly being covered over with a canvas tent to keep out the light. The exceedingly small piece of collodion film containing the positive microphotograph image was mounted in balsam beneath a cover glass on a standard 3 x 1 slide.” – The Microphotograph Slides Of John B. Dancer and Richard Suter by Roy Winsby
The practice of mounting microphotographs eventually became seen as frivolous by serious microsopists and their popularity waned. However, during the Franco-Prussian War the benefits for smuggling information on microphotographs meant that the technology developed by Dancer was given a new and very practical application.
Here is a list of Dancer’s Microphotographs.
Thanks to David Green for taking the photos of the slides.