San Francisco in 1906, Tangshan in 1976 and Izmit in 1999. Why does “Object of the Month” begin with a list of foreign places and years? Well, it’s not as far-fetched as it seems! All the places have been haunted by severe earthquakes, and even though Stockholm and the Swedish History Museum (as far as I know) have not been particularly exposed to earthquakes, it is actually ground tremors that are supposed to be about here in March’s object column.

AWe all know that ground shaking can be devastating for buildings and objects (not to mention people and animals), but surely no one here at the National Historical Museum thought that we would need to “earthquake-proof” our exhibited and stored objects – but that is exactly what has been done during a period from last autumn to a few weeks ago! The reason is the blasting work that has been carried out since 17 February in the large rock shaft that has been erected in front of the official building, i.e. the old barracks building, whose main entrance is usually used if you want to visit one of the museum’s or the National Heritage Board’s officials, archives or library.

The most spectacular object that was vibration-damped during this process, or vibration-isolated as the experts prefer to put it, was the so-called Skateholm grave. It was also really complicated to handle.

Many people probably ask themselves how to vibration-isolate a grave, you can’t do that, or can you? Well, in this case it went just fine!

Skateholmsgraven. PH๏τo: Ministry of Social Affairs and Health

Tomb that is 7,000 years old

The grave, which is about 7,000 years old, contains the skeletons of a man and a small child – the man holding the child in his arms – and is listed as a so-called specimen. To succeed with such a manoeuvre, the archaeologists have first dug a hole and exposed the skeletons and their grave gifts.

When they were satisfied with this part of the work, they strengthened the skeletons and all the surrounding sand and soil with many, many liters of strong-smelling clear coat. When this had dried and the objects were stabilized, a box of steel plate was built around the entire grave and the almost 800 kg “lump” was lifted up with the help of a mobile crane.

Some time later, it ended up at the Swedish History Museum and here in the museum’s old antiquities exhibition. Now it is exhibited in one of the most central places in the museum’s exhibition Ancient Times.

Ingenious vibration isolators

The box of sheet steel that encloses the grave stands on a roughly dimensioned base consisting of, among other things, longitudinal wooden studs. At eight points below these studs, ingeniously designed vibration isolators were placed, each with an upper load limit of 130 kg.

The insulators, which are made of compound steel and rubber, are actually designed for strictly industrial applications. The manufacturer makes the following recommendation: “… for the isolation of vibrations from low-speed machinery and equipment. Protects sensitive and lightweight devices from shock and vibration.”

Southern Swedish Mesolithic and industrial high-tech go hand in hand! A way, as good as anything, to give perspective on our fantastic history.