Gossip meeting “My latest microscopical acquisition”
Saturday 8th January 2022
The first meeting of 2022 was held on-line via Zoom and drew a good crowd of 44 members and visitors, including several from outside the UK.
Quekett members can watch a video of the meeting.
As usual with this theme there was an eclectic range of topics ranging from micro-manipulators to novel uses for Covid-19 lateral flow test devices.
Robert Ratford presented a fabric roll of instruments which he had bought for handling small items, samples and specimens.
Robert’s inexpensive specimen manipulation kit
He was particularly interested in transferring cladocerans for examination, and the loops, tweezers and probes were ideal.
The kits are priced from £2.99 to £4.99 on eBay and, remarkably, are marketed as “blackhead and spot removal kits”, but this shouldn’t put off prospective buyers as they have proved good for Robert’s purposes.
Gordon Brown presented his Zeiss KM microscope, which is not especially common and was only produced for a short time before being discontinued by Zeiss due to poor sales.
Gordon Brown’s Zeiss KM microscope
Originally intended for use in pathology laboratories where rapid turnover of specimens is needed, the KM has knob on the side that when turned rotates the nosepiece and changes the objective, and also operates a ‘zoom’-type condenser of variable focal length in which both area of field illuminated and illuminating aperture are varied together, so no readjustment is required. Only the brightness and aperture diaphragm need adjustment.
Zeiss KM – side view showing the objective changing knob
Changing slides is facilitated by a slide holder that has a tapered lead-in and automatic clipping. There’s also a folding carrying handle in the top, which makes it ideal for taking to meetings.
Zeiss KM – top view showing carrying handle
Optically the microscope is very good, but there is no option for a trinocular head and it also lacks a coarse focus, although the objectives are almost perfectly parfocal. If you can find one in good condition with a set of the black Zeiss objectives it may be worth buying as a go-to meeting instrument, but do check the stage carefully as they have a tendency to self destruct!
Gordon Brown also presented a new ring light which is less obtrusive than most available. It is produced as usual in China and sold on Aliexpress (https://www.aliexpress.com/item/1005001549422303.html?spm=a2g0o.90423184.108.40.206f754c4d7FyO5h) for £12.50 including VAT and postage. This unit is very thin and is powered by a 2A USB plug (not supplied) with a touch-sensitive switch and dimmer.
The internal diameter is a maximum of 58mm but it fits the DF Plan objective on Gordon’s Olympus SZH stereo exactly and looks like it is original equipment. A very worthwhile improvement and recommended, just don’t forget you’ll have to buy a USB/mains adapter of 2A to operate it properly.
Leonard Jannese was not able to attend the meeting, but he provided 3 photographs of his Olympus PMF Universal metallurgical microscope that he intends to restore and use. If anyone has experience of using this microscope, or has a user manual or a service manual, please let us know.
Olympus PMF Universal metallurgical microscope (left)
Olympus PMF Universal metallurgical microscope (right)
Olympus PMF Universal metallurgical microscope (top and accessories)
Les Franchi has found a new use for the now-ubiquitous Covid-19 lateral flow test kits as an everyday item as an aid in slide mounting.
Lateral flow testing kit
The sample tube and the snap-off handle of the swab are part of the kit. Dispensing appropriate drops of LOCA from the commercial tube is somewhat hit and miss for quantity and placement on the slide, too much fluid often emerges, meaning a messy clean-up once a coverslip has been positioned over the specimen.
This squeezable tube (right) will hold 1.5cc of fluid, enough for a number of slides, or kept in the dark for for another day. Using these tubes gives a controlled amount of mountant from the nozzle, even for sucking back any large excess. The plastic swab stick is handy for positioning the coverslip and applying gentle pressure where needed.
Lisa Ashby has recently been arranging the Member’s Auction and as a result has been speaking to a number of members for the first time; one of these was Colin Lamb. They had been speaking about Ernie Ives and Colin offered to send her a Dr Carpenter’s test slide that Ernie had made.
Ernie Ives’ test slide and Colin Lamb’s selection
Not only did he send the slide but he also sent four of his own mounts, referred to in his covering letter as “a few of my old rubbish”. As these have arrived on the day of the meeting she has not had the opportunity to look at these in detail but they are clearly far from rubbish and she is very much looking forward to spending some time with them.
Jacky McPherson described using a Barer & Saunders-Singer 1948 design micromanipulator she recently acquired from Derek Stevens, who had used it to measure the mass of Lycopodium spores by placing them on a fibre and measuring the resultant change in stress. He reported achieving a precision in the region of 10^-9 g, and Jacky intends to use the instrument for diatom work.
The movement may be controlled single-handedly in three dimensions: x and y are achieved by sideways movement of the joystick with great flexibility in positioning the bristle picker (Fig 1). Vertical movement is achieved by rotating the knob, thus enabling the bristle to be raised above the specimen plane.
Fig 1. Micromanipulator showing the joystick for moving the bristle
Travel of the bristle is managed by a slider in the handle that adjusts the gearing of movement. When slid to the top of the pillar there is a larger field of movement whereas slid to the bottom movement is restricted but more precise (Fig 2). Individual movements are not difficult but co-ordinating them is definitely a matter of practice.
Fig 2. Micromanipulator showing the low and high settings
For diatom manipulation Jacky has refined the attachment of a suitable bristle, one that will attract the diatoms by electrostatic forces so they may be selected and transported to a final mounting position. So far she has tried animal hair, glass fibre and steel needles, including acupuncture needles. The steel needles have been most successful.
Initially she set the device up on a Zeiss Stemi stereo microscope (Fig 3).
Fig 3. Micromanipulator and microscope
However, the magnifying power is really not suitable for picking diatoms. Jacky was using Shetland diatoms that Pam Hamer provided, and she has found they are really too small for this set-up, but she was able to get some results (Fig 4).
Fig 4. Shetland diatoms
Photomicrographs were taken with a Brunel LCMOS 5MP digicam using Toupview software.
Report by Peter Wyn-Jones