Just a quick question.

I've been trying to find out how widespread the use of telescopes or 'perspective glasses' would have been during the British Civil Wars of 1642-51, in a military context or at sea. I've seen an illustration from 1623 of a hand-held glass which looks to have been much like the military telescopes used during, for example, the Napoleonic Wars, and I gather by that date such instruments were already quite widespread in Europe. However, such information as I can turn up for that period seems only concerned with their use in astronomy and other scientific pursuits. I find it hard to believe that telescopes would not have been exploited by army officers or seafarers. Does anyone know anything?

AIUI it was more or less C18th that telescopes really came into widespread naval use - problems in producing lenses, and light losses through those lenses (more severe for a terrestrial than an astronomical telescope because of the erecting lenses) and the inordinate length of many such scopes made them difficult to use on board a ship - particularly as the need for an elevated line of sight to gain adequate range meant having to climb the rigging to use it.

I have seen a reference* that the Spanish had a story that Drake had some form of "looking glass" with which he could observe Spanish ships. The possibility is that Drake had a telescope some 20 or so years before it was officially invented.



*Thought it was in Rogers' Safeguard of the Seas but could not find it there.The other possibility is a library book about the Armada.

I have heard that a primitive telescope of some sort had been developed during the late 16th century. On the other hand, I have vague memories that the Spanish believed that Drake had some magic glass or mirror which he used to find their ships, when in fact he was just very lucky and/or good at finding them.