纪录片《大英博物馆世界简史》 062希伯来星盘（4）（在线收听）

At first sight this astrolabe looks like an outsized old-fashioned pocket watch with an entirely brass face. It sits easily in my hand - in fact it fills it - and it's a gleaming assemblage of interlocking brass-work, with five wafer-thin discs, one on top of another, held together by a central pin. On top of this are a number of pointers that you can line up with various symbols on the discs, and this will give you astronomical readings, or help you determine your position. An astrolabe like this one is designed for the particular latitude in which it is going to be used. The five discs here will allow you to get an accurate reading from any position between the latitudes of the Pyrenees and North Africa. In the middle of the range are the latitudes for the Spanish cities of Seville and Toledo.

And that tells me that this astrolabe was almost certainly made for somebody based in Spain, who might travel between North Africa and France. And what's written on the astrolabe tells us pretty clearly what kind of person must have been using it. It tells us that the owner is Jewish, and is learned. Silke Ackermann, the curator of scientific instruments here at the British Museum, has spent a lot of time on the astrolabe's inscriptions: