History group

Tony Kearsley, mineralogist, who worked at the Natural History Museum, London until he retired to Ravenscar, was the guest speaker at the February meeting of the group. He worked in the Imaging and Analysis Centre, which deals with some of the many and varied enquiries from members of the public and commercial organisations. The museum has 900 workers (which includes 350 scientists) and contains over 80 million specimens.

The public enquiry service at NHM is free, and specimens came to Tony to find out about their chemical composition. He did this by scanning electron microscopy and X-ray microanalysis, using a microscope in which most of the air surrounding samples was pumped out (not all because this would have left samples vulnerable to damage). This process produced high resolution images that showed the various components – and thanks to stereo anaglyph glasses we could view these in 3D on the projection screen.

One analysis example was a huge gold nugget, that turned out not to be pure gold (10% was silver). An enquiry about a wooden barrow from the Whitefriars glass works (“Can we put it out for the public to handle?”) was decided quickly by the analysis of powder residue in it – which turned out to contain arsenic – answer “NO”.

Many of the ‘meteorites’ that were sent to the museum turned out to be something quite different. Most were pieces of artificial metal alloys, or slag from smelting. A round object that had melted it’s way through a plastic conservatory roof was revealed as a piece of burning plastic foam, and another sample was one of the inner components of a firework! The Centre at NHM has also done sponsored enquiry work for space agencies, monitoring the cosmic dust impacts on the Hubble telescope, and working with NASA looking at impacts on the “Stardust” spacecraft.

Objets d’art and jewellery can be analysed to find out if they are real or fake – an example being the composition of carved serpentine masquerading as the much more valuable jade. The museum also collaborates with the nearby V&A Museum. Possibly the most alarming sample sent in as an enquiry turned out to be a corroded World War One grenade – necessitating the evacuation of the department and the attendance of the bomb squad!

Guest speakers at the next meeting on Tuesday 21 March, at Ravenscar Village Hall, 2pm, will be Tom and Lindy Rowley talking about Scarborough fisher folk. Tom is a retired fisherman and Lindy was instrumental in setting up the Scarborough Maritime Heritage Centre.

Subscription are due at the March meeting.