Curiosity of the Month

After a short break, Curiosity of the Month is back with a peculiar instrument discovered by Derbyshire Museums Manager Ros Westwood. Over to you, Ros:

A few months ago I had the opportunity to go and explore the contents of the Petrifactioner’s workshop. Visitors get to peer through the window and the door into a tiny room where a man making stone ornaments from Ashford Black Marble may have sat, surrounded by his tools and work he had made. His working glasses have been left on the bench, and he seems to have just shut up shop, leaving one of those marvellous notices pinned on the door: Back in five minutes.

Buxton Museum & Art Gallery Ashford Black Marble displays 2

The tools hanging on pins and thrust into jars relate to his trade, so there are rasps and stone cutting clippers and scribes for marking the patterns. But some oddities seem to have sneaked in, and this month’s curiosity is definitely in the wrong place.

First of all there is a case, made of leather and rather battered and worn. Handing on a peg on the wall, it looks like it might hold a sheath. Inside it is stamped in gold: Murray and Heath 60 Jermyn Street from 43 Piccadilly. It is empty, except for a scrap of paper in J.W.Jackson’s handwriting, folded into it:

Note: Craniometer is 3mm wider at ends of arms than at base of same. This figure to be added to all measurements made with the ends of arms!!” (his two !!)


But what am I looking for? Is it even here? A craniometer, I suggest, will measure a cranium, in other words, a skull. There is one which looks like a huge pair of callipers in the Boyd Dawkins room, but clearly, that won’t fit into this case. Then I recall a photograph of Jackson measuring the skull with a curious instrument.

And here it is I think – but all folded up – and clearly not a tool for working stone with!


Folded up, it looks like a double ruler, made of wood (possibly box), golden with age, with one of the rules cut in the middle. They are marked on the top side in inches, the numbers neatly stamped in an old fashioned, 1920s numerical script. The measurements are in millimetres on the reverse, indicating that this was a tool for use by international scientists. The ends are cased in brass. With care you can fold out the cut ruler on neat hinges so they rest at 90 degrees to the main arm. Alongside one of the arms are two wooded turned markers, one fixed at the end, the other moving along the scale.  And one of the arms is marked as well Murray and Heath – Opticians – 43 Piccadilly, London. Interesting – the instrument was made before the business to new premises in Jermyn Street, at the heart of London’s fancy goods quarter.


So how to use it? Clearly the two arms can be fitted either side of a skull and measurements of the height and width taken, almost regardless of whether the skull belongs to a shrew or a cave lion. And what of the pegs? Well, the clue is perhaps in the trade of Murray and Heath, Opticians. These pegs can be used to measure the distance between the eyes – or any two other points.

London had an excellent reputation for instrument making, and Jackson must have saved hard to afford this elegant tool which he would have used often at his desk at Manchester Museum. But clearly, he needed to remember that with time and use the hinges had eased and calibration had changed, so his little note remains, and we can still measure items in the collection in the way he did.

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About benjonesmuseum

I have been working at Buxton Museum and Art Gallery for 20 years in one role or another, working on various projects. Currently, I am a Visitor Services Officer for Collections in the Landscape, a project that I am very excited about. I am known as BJ, or Big Ben. To the local youngsters I am called Seventies Man or 118.

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