This morning, upon skimming back on my previous posts about Steampunk tech and Steampunk in general, I realized that I hadn't yet touched upon the science of optics. Now, this is a fascinating topic (I say that about everything though, so take it with a grain of salt), because the science of optics itself traces its way 23 centuries ago to the third century B.C. and the ancient Greeks. Our old friend Hero of Alexandria is mentioned in the extant literature on the topic, as is Euclid (who you may remember from geometry class). Both of these men composed major works on the nature of light and reflection, which set the stage for later innovations into lenses for sight correction and telescopes.
Euclid theorized (wrongly) that sight worked by beams shooting from your eyes to the object itself. He also noted that light travels in straight lines and described the laws of reflection. Hero used a geometric method to prove that the path a ray of light reflected from a plane mirror takes is shorter than any other reflected path that might possibly be drawn between the reflected object and the point of observation. A circa 140 AD text attributed to Cladius Ptolemy also included a study on refraction.
It wasn't until 965 AD, and the work of Ibn-al-Haitham (sometimes called Alhazen in extant literature) that we see the beginnings of optics as we know it today. Alhazen worked with spherical and parabolic mirrors in his experiments, and was aware of a concept called spherical aberration (a point of light looks different on the outer edge of a spherical lens as opposed to the inner edge).
The 13th century saw the work of Robert Grossteste (a professor at Oxford) who theorized about the nature of light, his student Roger Bacon who worked with convex lenses to magnify objects, and Witelo's Perspectiva, which was destined to become the premier text on optics until the 17th century.
Isaac Newton, Johannes Kepler, and Galileo Galilei -- the giants of optics -- all operated in the 1600s throughout Europe. In 1608, Hans Lippershey -- a Dutchman -- was the first one to build a working telescope. From here optics exploded with developments in knowledge of light and magnification all through the 17th, 18th, and 19th centuries -- Kepler helped refine both the telescope and microscope, and from Newton's work on Optics, later scientists were able to discern a whole host of theories about light and the way it acts.
Well into the 19th Century, and still today, there are advances in telescopes and microscopes ongoing, which allows us to see farther into the distance of space and deeper into the microscopic realm.
So what does this mean for Steampunk? Glad you asked that question, dear reader (Yes I know you didn't ask. Work with me here).
It means that when it comes to magnifying instruments and the like, the sky is pretty much your limit. Gail Carriger has a device called "glassicals" in her Parasol Protectorate series, which amount to a set of glasses with lenses that flip down to allow ever-increasing levels of magnification. Because the science for all types of optical tech dealing with lenses existed (except for the fun electron microscope and varieties of other entertaining toys that allow you to see into people's bedrooms from halfway around the world), you have little to no historical fact stifling your creativity when it comes to magnification tools.
Case in point, Moriah at several points uses binoculars to spy on people. In a short story I finished writing last night, Dmitry (a side character in CaN) uses special goggles to see from a distance and protect his eyes. The moral of this lengthy post is basically that, when using optics, stay away from anything electric and you are good to go for a Steampunk extravaganza.
ADDENDUM: Here's a full timeline of developments in Optics.