Down House Microscopy Weekend

Saturday 17th and Sunday 18th August 2024

Organising the display

Tim Fullick, a Quekett member and volunteer at Down House near Bromley, suggested the Club join in a celebration of Charles Darwin’s microscopes by putting on a microscope display.

Down HouseDown House

Darwin and John Quekett were contemporaries and Darwin certainly contacted Quekett. There was some trepidation, but a core of Club volunteers thought they could develop some useful themes, and there were enough of us to cope with displays lasting two full days. Wanting to focus on the microscopical work done by Charles Darwin, we decided to focus on three aspects; barnacles, rocks and fossils, and insectivorous plants. Several of Darwin’s microscopes are displayed by Down House but cannot be handled, so we decided to show live images on somewhat less valuable instruments that visitors might be able to adjust and focus themselves. We also wanted a table with simple microscopes and some samples that younger children could handle and investigate without too much supervision.  Planning for all this took about a year, with those members producing specific displays reading about Darwin’s work and trawling the Internet for as much information as possible. Luckily there is a lot available, with several organisations making Darwin’s letters and items freely available.

In recent years, Tim Fullick has acquired examples of microscopes of the types used by Darwin in his investigations, and these were exhibited alongside specimens of the organisms he worked on using them. They included a Smith & Beck Large Best achromatic microscope dating to 1847 alongside information on the barnacles studied by Darwin. There was also a Noveau Petit Modèle by Edmund Hartnack dating to 1873 alongside examples of the plants Darwin examined. A smaller Cary-Gould box-mounted microscope dating to 1826 had a slide of the colonial animal Flustra (a bryozoan). These were beautiful antique microscopes, and Tim had set them up with more information about the specimens Darwin examined on his microscopes. Visitors were able to see these samples on microscopes of the time.

Tim FullickTim Fullick

Smith & Beck Large Best microscopeSmith & Beck Large Best microscope

Hartnack Noveau Petit Modèle microscopeHartnack Noveau Petit Modèle microscope

Cary-Gould box-mounted microscopeCary-Gould box-mounted microscope

The room set aside for the display at Down House was quite small, so it was decided that only about 12 people should be admitted at a time to avoid too much crowding. In the event, queues formed and there was a very steady procession of people coming into the display. There were over 400 visitors to the House during the weekend, and it was estimated by the volunteers that almost all of them visited the display. There were lots of families and a significant number of overseas visitors, including some from China, from Spain, from Argentina and from the USA.

For the Club display

Grenham Ireland volunteered to try and set up a display showing live barnacles which would intrigue children. He spent some months collecting specimens from Poole Harbour to see how to maintain them out of the sea so they showed their feeding behaviour. During the display this worked magnificently. Joan Bingley concentrated on insectivorous plants and was joined by Jay Holmes from the USA who has studied Darwin’s work in part for his job at the American Museum of Natural History. It was so good to have his enthusiasm and knowledge over here.  Pam Hamer and Stephen Parker set up a display of rocks relating to Darwin’s travels on HMS Beagle and his developing understanding of geological processes which were important in developing his thinking on evolution. Martin Parnham and Lisa Ashby completed the team, each spending a day showing the younger visitors interesting specimens to view with the simple microscopes.

It might be best to hear from each member how their display succeeded so magnificently.

Grenham Ireland

Grenham described his 3 microscope set-up.

Barnacle displayBarnacle display

  • On the left was the rock with attached Austrominius modestus barnacles (an invasive species) submerged in a black bucket and viewed with a Chinese industrial microscope with HDMI output to a monitor.
  • In the centre, I had a small stereo microscope to show a sample of live plankton lit against a dark background. I had hoped to show live nauplii larvae, but the sample was composed almost entirely of copepods.
  • On the right (not shown) was a semi-permanent slide I had made of a dead barnacle which showed the structure of the cirri, on a Zeiss WL microscope at relatively low magnification. This image could also be shown on the monitor.
  • I also had a pot of preserved stalked barnacles attached to a broken bottle which were pickled in 1927 and which I had borrowed from the Bournemouth Natural Science Society Museum,  and some dried ones as well.
  • I used my laptop to show some videos I had taken of live nauplii and cypris larvae at high magnification.
  • Finally, there were two A4 sheets – one with information on barnacles and the other explaining why barnacles were important for Darwin.

Most of the visitors had no idea that barnacles were active in the way shown, feeding with their legs through their opercula. However, one or two visitors knew all about the reproductive apparatus of these immobile hermaphrodites, a feature I had not emphasised in the demonstration!

Grenham Ireland and Martin ParnhamGrenham Ireland and Martin Parnham

Joan Bingley and Jay Holmes

Joan and Jay had a variety of microscopes including Jay’s own 200-year-old microscope by Robert Bancks and described their display as follows.

Joan and Jay hosted a table highlighting a few of the genera of carnivorous (or insectivorous) plants that Darwin studied. His interest was sparked by a bog walk in Hartfield when he counted 31 flies on a total of 12 Drosera rotundifolia. He wondered about how the features of this plant may have provided some advantage to the plant and provide an opportunity to test his theory of Natural Selection. This led to the publication of his book “Insectivorous Plants” 15 years later in 1875.

Using a variety of microscopes spanning almost 200 years, participants observed Drosera leaves enrolled over prey under a 1920 dissection microscope, and Drosera glandular tentacles under a 1960s Wild M11 binocular compound light microscope. We also observed two species of Utricularia (bladderwort), viewing their aquatic traps under a modern stereo dissection microscope and comparing that view to the view through a Robert Bancks single lens microscope from 1825, similar to the one Darwin had on the Beagle.

Jay Holmes setting upJay Holmes setting up

Insectivorous plants displayInsectivorous plants display

Utricularia through Bancks microscopeUtricularia through Bancks microscope

Bancks microscopeBancks microscope

Bancks microscope from aboveBancks microscope from above

Wild M11 microscopeWild M11 microscope

Joan provided the beautiful Wild M11 (updated with an LED light source), the 1920s dissection microscope with its brass column and beautiful black lacquered base with its graceful curves, and the modern student stereo microscope which was an excellent example of the kind of microscope that could start one on one’s own journey exploring the natural world in one’s own yard or neighbourhood. The Bancks microscope travelled across the ocean, by jet this time, from New York with Jay.

The table (as well as the whole room) gave participants the chance to learn about Darwin’s questions, observations and how his thinking helps us understand nature around us, and also get a chance to explore the history of microscopes.

Pam Hamer and Stephen Parker

Pam Hamer was joined by Stephen Parker for one day and they displayed hand specimens of rocks and thin rock specimens with a variety of microscopes.

Rocks displayRocks display

Pam writes

Some years ago I had a fabulous holiday which included a ship voyage through the Magellan Straits and Beagle Channel at the southern point of Chile and Argentina. At one point we landed in a large bay where there was a stone plaque commemorating Darwin’s landing there in 1833. In his book “Voyage of the Beagle”, Darwin refers to collecting rocks here, and thanks to the curators at the Sedgwick Museum in Cambridge I was able to obtain a photograph of a sample in Darwin’s rock collection, housed there, from Tierra del Fuego. A thin section was later made of the rock and it was identified as a diorite. There was a PowerPoint show running on a computer which told the story of my interest in this specific rock. A hand sample of diorite could be compared with granite, and a stereo microscope and a polarising microscope displayed thin sections of a diorite and granite.

Many of the rocks from the Darwin collection are in the Open University Virtual Microscope project on the Internet (Charles Darwin’s Rocks). This is an interactive display with descriptions of the minerals in the rock and images in both plane-polarised light and crossed polars that can be manipulated to show features like pleochroism, extinction and polarisation colours.

Among the visitors, an Argentinian family were delighted to see that Darwin travelled extensively in their country, and even referenced their home area in a section in his book. The pieces of rock proved to be attractive to children and older ones were fascinated by the effect of rotating the stage of the polarising microscope to see the polarisation colours changing on the thin sections.

Stephen writes

I brought two Swift polarising microscopes made about a century apart. These showed various sections of granite to illustrate Darwin’s interest in geology, in particular his theories on the emergence of different types of rock from magma. He thought gravity caused larger crystals to sink and thus create course grained rocks below finer-grained; we now know that in reality the difference is due to differential cooling, but he contributed to the debate.

Swift polarising microscopesSwift polarising microscopes

The late 19th century brass folding polarising microscope was used to show 19th century slides, cut thicker than the modern standard, but therefore more colourful. The modern Swift, equipped with a digital screen, showed recent slides from Glen Coe and other Scottish localities, sometimes with the addition of a first order red plate.

I also brought a later, Society of Arts, version of single lens microscope and child-proof slides, for children to experience the type of microscope Darwin took on the Beagle. There were also atlases of rock sections for visitors to inspect.

Stephen ParkerStephen Parker

Martin Parnham and Lisa Ashby

Martin wrote of his day – the first Club display he has attended.

The Club set up a children’s table, Pam Hamer provided a stereo microscope and a simple inverted one. I manned the table on the Saturday providing a USB scope with inbuilt lighting and screen. The Saturday specimens were a stained head louse slide, sugar and salt crystals, living woodlice and snails, a pound coin, and most importantly the children’s own fingers!

Children’s tableChildren’s table

Their reaction was delighted amazement, it was very clear that none had ever used anything like a microscope before. Talking to the parents, it seems most of them also had a very limited school experience of them. The USB scope with screen proved to be the easiest for them to use, they are very familiar with screens having ‘used’ their parents’ phones / computers from a very early age. To them this was a natural way to view images. They tend to struggle more with eyepieces. I am sure it was a very worthwhile experience for them and one we should try and repeat.

Lisa wrote of her day.

I had three microscopes on my display.

  • A Telmu battery powered inverted microscope which had been donated for outreach by Stephen Parker. This is fitted with a ×10 wide-field eyepiece and ×4, ×10 and ×20 objectives. On this I rotated slides of a louse, an ant, a slice of pine or a fruit fly.
  • A Brunel DM6 battery powered stereo microscope with ×10 wide-field eyepiece with a red admiral wing.
  • A mains-powered Brunel stereo. On this one, guests were encouraged to move samples around and were able to look at a sample of spice seeds including cumin, coriander, peppers, fennel etc, bird feathers (woodpecker, jay and parakeet), and a sample of sparkly nail varnishes. As well as looking at their own hands to compare the skin either side or see if they could see their own fingerprints.
  • I also had some hand lenses to look at bugs in resin. Usually the largest specimens prove the most popular, but on Sunday it was the small sea horse.

My display was intended for younger visitor but also demonstrating to the adults that you can find a variety of things in and around your home that are interesting. Entry level microscopy doesn’t have to be expensive!

Although this was my aim I was delighted that many of the adults that visited were equally interested in the items. People seemed genuinely surprised by being able to see the scales on the butterfly wings, and I was able to tell them about Victorians using the scales to create microscope slide pictures. I had also recently seen an article from the 1920s in which these were described as having no scientific value but they were an amusement for the ladies, I can only assume that we should not have our heads turned by science! I had a couple of teachers who were interested in the nail varnish display as they could repeat this easily within their classes, as well as someone who asked why a jay’s feathers only have blue colouring on the top yet the white dots on a woodpecker feather are visible on both sides. I didn’t know the answer, which just goes to show outreach can inspire and raise questions for all parties.

Lisa AshbyLisa Ashby

Summary

This event was very much enjoyed by all the members who displayed microscopes and specimens, though it was quite tiring. It was great to welcome Jay, so enthusiastic, and the person who produced many of the images of the day shown here. Thanks to all the volunteers. Perhaps a measure of the success is that Down House have invited us back next year to set up another display of microscopes and specimens! More volunteers needed!

VisitorsVisitors

Pam Hamer, Grenham Ireland and Lisa AshbyPam Hamer, Grenham Ireland and Lisa Ashby

Tim Fullick, Joan Bingley and Pam HamerTim Fullick, Joan Bingley and Pam Hamer

Charles Darwin coffeeCharles Darwin coffee

Report by the participants, most photographs by Jay Holmes

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