17th cent. telescope found in Delft

Archaeologists in Delft have uncovered what may be the world's oldest telescope in the digging works for the new railway tunnel in the city. Specialists from the Boerhaven museum in Leiden have confirmed that it is a telescope, after looking more closely at the rusted tin tube, thinking at first that it was a bullet chamber, the Volkskrant reports. The antiques specialists concluded that it is a telescope from the 17th century. The primitive grinding work, and the poor quality of the glass lenses, full of bubbles and unevenness. The telescope can magnify up to five times, which was tested in the lab in Leiden. "Especially the frontmost glass is so primitive that it was hardly recognizable as a lens", says curator Tiemen Cocquyt of Boerhaven. "But after cleaning, the telescope really works again."

The Dutch telescope was invented in 1608 in Middelburg. Shortly after that, Delft became a well-known producer of lens viewers, according to historians. Engravings from that time period reveal similar viewing apparatuses, but up to now, none were believed to have survived in the Netherlands. Worldwide, only 20 are known to exist. The oldest kept scopes in the Netherlands are only from the second half of the 17th century, among others from the Christiaan Huygens collection. "In any case, this is the oldest example in the Netherlands, and possibly even internationally the oldest", says scientific historian professor Albert van Helden of Utrecht, a specialist and enthusiast on the subject of old optics. Helden suspects that the oldest Dutch telescopic devices have since rusted away as they were made of tin plate. Brass was used in France and Italy, for example, which is better preserved.

The telescope was discovered in an old submerged ditch, and may have been used by an affluent citizen of Delft at, for example, public gatherings. "The magnification is actually inadequate for military use, man had better instruments for that quickly."

Van Helden claims that this discovery is an unknown, primitive scope, which already means that it must originate from well before 1650. "Towards that time, no tin was used and much better glass that is ground better." Curator Cocquyt does not think that it is a knock-off from a later time. "The tin looks gilded in places, which points to the fact that it was a serious and valuable instrument. Only: in a time when the technique was not very advanced."

The telescope will be on display at the De Prinsenhof Museum in Delft from next week.