Round spectacles like those from pre-Revolutionary times continued to be made into the Revolutionary era, and can, in fact, be seen on many depictions of Benjamin Franklin, the father of the bifocal concept, himself. However, a time of clear change was underway in the technical sphere as much as in the political, and this is clearly visible in many of the old glasses from this time.
We have already looked at how advances in grinding technology allowed the creation of many highly functional pairs of oval and elongate hexagonal lenses. This, in turn, offered a wider field of view to the wearer of these old glasses. To judge by the number of surviving examples, the new shapes were very popular, probably because of their basic convenience.
However, changes were evident in other areas of the design of old glasses in the Revolutionary period, too. Most notable of these are alterations to the temples, with a very different approach to these than that which was used only a generation earlier.
Revolutionary era temples on old glasses
In one regard, the newer style of old glasses had not changed from the spectacles of those from the times of the Salem Witch Trials. Their eyerims and bridges were still constructed in such a way that they had little purchase on the nose, and nose pads were lacking from their design. Therefore, without tying them onto one's head using the temples, they would either slip down the nose or fall off entirely.
Since the Revolutionary period witnessed the rapid decline of the huge, fluffy powdered wigs that many had affected a generation or two previously, the large loops at the end of the temples from that period – meant to be woven into the wig – also disappeared in American spectacles at least. Large wigs continued in use in France until the end of the Ancien Regime, but American wigs became smaller and eventually fell out of favor completely.
Therefore, nearly all old glasses from this time in the Colonies have small loops, again reminiscent of the eye of a needle, writ large. These were used in the same fashion to tie the spectacles around the user's head using either a ribbon or a cord.
The design of temples found on vintage glasses changed radically at this time, however. Instead of folding, they became sliding, using a slot and rivet arrangement to allow the two parts of each temple to telescope together into a much shorter form for storage. A rivet on one piece fit through a slot on the other, allowing the temples to be instantly extended or retracted. This neater arrangement involved less tiny hinges and thus lessened the chance of breakage.
Some temples continued to fold at a slant, one above the other, behind the eyerims. Others now crossed over each other in the manner of modern eyeglass temples. These old glasses looked considerably more like our modern glasses, and this familiarity, plus the sliding rivets of the temples, helps you distinguish them quickly and certainly from pre-Revolutionary models.
Materials used for old glasses from the time of Franklin
Though manufacturing and design had advanced, materials technology remained the same as in the previous period. Bronze, brass-bronze alloy, steel, silver, and gold were still the metals used for spectacles frames at this time. Lenses were still “glasses” – ground from glass – or “pebbles” – ground from quartz using an iron wheel, diamond dust, and oil of brique.