Gossip meeting “My latest microscopical acquisition”

Tuesday 11th July 2017

Several Quekett members braved the downpours to come to this popular annual meeting in the PA135 Meeting Room in the Natural History Museum, and brought along some of their latest microscope-related acquisitions. There wasn’t an introductory talk this time; each member spoke briefly about their exhibit and then the gossip began.

Dennis Fullwood brought a box of foram slides obtained on eBay from Klaus Kemp, and 2 other slides. One was a diatom arrangement by Eduard Thum, shown on one of the Club’s trinocular Zeiss Standard microscopes and displayed on the television via a Canon EOS M mirrorless camera. The other was a whole mount of a spider apparently by Hancock, shown on one of the Club’s stereomicroscopes. The spider had one leg shorter than the others, so it must have been immature because mature spiders lose the ability to re-grow legs.

Dennis FullwoodDennis Fullwood

Thum diatom arrangement on televisionThum diatom arrangement on television

The foram slides included ones made by Arthur J. Doherty, A. Newton, Robert Pettigrew, Jun. and W. G. White.

Foram slidesForam slides

Foram slidesForam slides

John Tolliday showed a mains-powered Chinese LED microscope lamp that comes with a ring-light, two 3W white goosenecks and a 3W UV gooseneck. Any two can be connected at the same time, with separate brightness controls. The eBay seller in Hong Kong is lapsun_kit.

John TollidayJohn Tolliday

LED spotlightsLED spotlights

Maurice Moss brought a piece of bornite (peacock ore) that he had recently purchased for £1.50 from the Booth Museum of Natural History in Brighton. This mineral is a copper ore and exhibits iridescent tarnish. In room light it was colourful, and it looked spectacular under Alan Wood’s shadowless illuminator.

Maurice MossMaurice Moss

Bornite (peacock ore)Bornite (peacock ore)

Nigel Williams brought an Amos Topping slide of a lamprey. It did not have a maker’s label, but the eBay seller referred him to the Amos Topping slide on plate 35 in Microscopical mounts and mounters by Brian Bracegirdle and the handwriting was identical.

Nigel WilliamsNigel Williams

Amos Topping slide of lampreyAmos Topping slide of lamprey

Pam Hamer used the Club’s Prior stereomicroscope to show a piece of Purbeck marble that had been polished to reveal the fossil shells. It is not a true marble but it can take a fine polish; it contains the fossilised shells of tiny freshwater snails (Viviparus). The specimen was given to Pam by a visitor to the Langton Matravers meeting in April.

Pam HamerPam Hamer

Purbeck marblePurbeck marble

Phil Greaves showed two of his recent acquisitions. One was a Tiyoda pocket microscope, an inverted design with a clamshell case that can completely enclose it. It takes a single objective and depends on available light; it has no mirror or condenser and has to be protected from extraneous light. This model was introduced in 1950 and was still being sold in 1995, but is not often seen. To demonstrate it, Phil used a Harris Biological Supplies slide with 3 different sections of Tilia.

Phil GreavesPhil Greaves

Tiyoda pocket microscopeTiyoda pocket microscope

Phil’s second object of desire was an exquisitely-made Schleck lever compressorium dating from the 1840s. Turning the thumbscrew applies pressure to the specimen. The coverglass is glued in place with shellac, and so would not be simple to replace if it broke.

Schleck compressoriumSchleck compressorium

Stephen Parker has recently acquired several items from the estate of Quekett member M. S. Gillett, and showed a Baird & Tatlock catalogue, a Reichert Zetopan DIC brochure, a home-made reflecting objective, and a home-made tilting mica compensator with a motor to make it spin.

Stephen ParkerStephen Parker

Reichert DIC brochureReichert Zetopan DIC brochure

Baird & Tatlock catalogueBaird & Tatlock catalogue

Alan Wood demonstrated a shadowless illumination technique that was published in 2008, using an LED ring-light that he bought in 2012, but he had not used the technique until April 2017 for the Quekett stand at the Members’ Day of the of the Amateur Entomologists’ Society, so that makes it recent.

Mary Morris with Alan Wood’s exhibitMary Morris with Alan Wood’s exhibit

By placing the ring-light on the stage of the microscope, pointing upwards into a white bowl (with its base removed), almost shadowless illumination can be produced, avoiding most reflections and revealing iridescent and other colours.  The specimen needs to be placed in the centre of the LED ring, with a background of any suitable colour.  Depending on magnification and working distance, you may need to prevent direct light from the ring-light reaching the microscope, so that the image is not spoiled by flare; this is easy to do with a cylinder of white paper just inside the ring of LEDs and/or a piece of white card with a circular hole on top of the bowl.

Construction of shadowless illuminator from LED ring-lightShadowless illuminator, showing (top left) specimen pinned into a Plastazote disc, (top right) ring of white paper, (bottom left) inverted bowl with base removed, and (bottom right) the complete illuminator.

To demonstrate the illuminator, Alan used the Club’s Meiji stereomicroscope and a pinned bluebottle (Calliphora vomitoria (L.))

Bluebottle (Calliphora vomitoria) using shadowless illuminationBluebottle (Calliphora vomitoria) using shadowless illumination (body length 10.5 mm)

Kit Brownlee asked if this technique could be used to light micromounts (small mineral specimens) for photography, so we borrowed Maurice Moss’s peacock ore and it looked great.

Report and photographs by Alan Wood

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