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AO Recollections

AO Glass plant and Dads demonstration to me of Prince Ruperts Drop-
an experience I will never forget!

This 1970s photo shows the AO Glass plant "Claw" roof ventilation behind the power house smokestack in Southbridge
as it appeared at the time the Glass plant was in operation. This facility closed in 1979 and the claw was subsequently removed.
See how the roof looks in 2010
Optical Heritage Museum photo

In the late 1960's, Dad was explaining to me the science of how glass was made and subsquently decided to demonstrate the properties of Prince Ruperts Drop. Since he had worked at AO since 1947 and was knowledgeable on this and many other Industry related topics, I looked forward to his science demonstration. He was a great teacher and benefit to this day from his having tutored me.

One hot summer day he brought home a "prince ruperts drop" to teach me a physics lesson. In the end, we both learned more than expected! He explained the science by the fomation of this unusually shaped piece of glass. It is formed when molten glass is dropped into cold water. The sudden cooling forms a hard, drop shapped piece of glass that is quite beautiful but also dangerous. For more of the science and to see a video on this topic, check out the links below.

In any case, he wisely put on a pair of AO Safety goggles and had me do the same. Since it was very hot that day, he (and I) were wearing short sleve shirts, a major flaw in his demonstration. I remember vividly that we both walked outside our home on Litchfield Ave and stood in the street ready to see how this demonstration would unfold. He explained that all it took to complete the demonstration and see how the drop would explode would be to break through the outer thin layer formed by the sudden cooling of the drop. He decided to snap the very end of the tail of the drop with a pair of plyers.

I stood back (not far enough) and Dad proceeded to snap the tail of the glass drop. Withing a flash, there was a sound of the glass pulverizing into millions of tiny glass scards that were so small that little remained of the drop that he was holding in his hands. We both soon realized however, that his arms and to a lesser extent mine had stopped many of these projectiles and there were dozens of tiny cuts from the glass on his arms with small amounts of blood immediately evident. This impressed us both as to the dangers of this type of demonstration. Fortunately, since we were both wearing AO Safety googles we both averted much more serious injuries that could have been life altering.

Check out this video of the Ruperts Drop when it breaks

AO Glass plant furnaces in operation in the mid 1970s - Optical Heritage Museum photos

Glass plant with the Claw on the right section of the above 1970s photo

Glass chunks from AO's Glass plant operation

More about Glass and Spectacle lenses on AO/Optical Heritage Museum website

More AO Recollections

Recollectionof Southbridge


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Last update July 12, 2010