Although leather and horn vintage glasses frames are very common on the earliest American-made spectacles and pince nez, many of the surviving pre-Revolutionary spectacles have metal frames.
This does not necessarily mean that such vintage glasses frames were more common than those made out of organic substances, since due to cost considerations, the reverse is almost certain to be true. Instead, these metal frames stand a better chance of surviving the test of time, though leather and horn can survive for many centuries if kept safe from wet, fire, and the nibbling of hungry rodents.
The pre-Revolutionary spectacles with metal vintage glasses frames that you are apt to encounter are almost all imports to the Colonies from England, or even from the Continent. This does not lessen their interest or historical significance, however, since they are still an organic part of the history of antique glasses in the future United States.
Lenses that were “just good enough”
The 17th century attitude towards optically correcting glasses was somewhat different from our own day's attitude. While today, we attempt to match the magnifying power of glasses exactly to the needs of the user's vision, creating as clear and perfect a correction of ocular problems as possible, the 17th and early 18th century attitude was more focused on seeing well enough to work or read, rather than seeing perfectly.
This attitude probably sprang mostly from the fact that nothing better was available at the time – technology and individual economics did not allow most people to find spectacles that were a perfect match for their vision problems.
Benjamin Franklin's invention of the bifocal lens – which took place either in the 1730s or 1780s, depending on whether his letters or the traditional date given by historians are lent more credence – is probably the first major break with this attitude, since it is an attempt to give the wearer more precise control over their clarity of vision at different distances.
Since this happened towards the end of the pre-Revolutionary period, however, most of the lenses you will find in metal vintage glasses frames from this era may be only passably ground and have visible defects, which in no way detracts from their value but helps as a clue in identification. Some expensive pairs for the mercantile elite, of course, are probably masterpieces of grinding and framing, since these individuals could afford to import the best vintage glasses frames and lenses from abroad.
Metal vintage glasses frames materials – steel and bronze
Vintage glasses frames from the pre-Revolutionary days are mostly made out of bronze or steel, which provided sturdy eyerims, bridges, and temples which, in surviving examples, are usually unbroken to this day. Metal had the advantage over tortoiseshell or horn that in the event it was broken, it could be mended by any competent metalworker, besides being resistant to time and environmental conditions (and inedible to rats and mice).
These steel and bronze vintage glasses frames were mostly made for the lower to middle end of the trade, while more affluent users would either buy higher quality steel imported spectacles, or else the silver-framed “deluxe” types produced by famous silversmiths in England, bearing their hallmarks, monograms, and often a depiction of the current King's head as well. All of these are described in future articles about vintage glasses frames.