Post St. Patrick Day Post...

As a tribute to St. Patrick and perhaps St. Brendan’s journey I have decided to finish my discussion on a nautical piece normally thought only as a crude time keeper for the Dutchmans, English, or chip log.  As mentioned in a previous blog post I said I would go into more detail about how sandglasses are made if only for the purpose of showing the changing society in northern Europe in regards to technological and social change.  The first hourglasses were most likely made in the Mediterranean portion of Italy or France during the 13^th century, where Roman period glass production continued after this namesakes fall.  The Roman Empire in its last days had become a God fearing republic and it would be this vestige of the imperial administration which would preserve many texts and technologies from oblivion.   While technology and literature where preserved in the case of the humble sandglass the purpose of this invention and its originator are now lost to history. 

            The key to making a sandglass like those used onboard ships for navigation or even simple timekeeping in regards to religious services onboard ships would be the manufacture of the glass vials or ampoules which contain the glass which the sand falls through.  Glass was used in the near east for thousands of years as a form of currency and beads and trade discs are common in the archaeological record.  It was the Romans from which we know the most and assume our current predecessor’s knowledge comes from.  There appear to be three types of vials, globes or ampoules.  The first type is distinctly pear shaped and seems to be favored by the Low Countries and some of the northern German states.  This form of vial has a low push up and is characterized as stated before by a pear shaped body form tapering to a mouth which has been shaped expanding the neck and squaring it on a marver.  Another form is more globular and appears to be more common to the countries of the southern German states and the Mediterranean which either can have a low or a high push up.  The third and final form which I have observed is the form most common in late Renaissance and early modern church sandglasses which almost always have a conical form with a high push up.

            Regardless of form the technology to produce these vials, globes, or ampoules is the same.  The Romans as far as we know were the first to produce large glass containers, although this technology most likely has earlier precedents.  The glass is melted until it has no crystal structure and is picked up from the furnace on a blowing rod made of metal, in most cases iron, but early pieces could have been bronze.  The glass is then spun and blown into a vial until it is the proper size and the glass blower uses a set of tools called jacks to manipulate the shape of the piece.  If straight sides or a consistent diameter are required the piece is then rolled on a metal marver as stated previously.  The piece is then transferred to a pontil rod which is another blowing rod with less glass on it which is attached to the base of the vial so that the neck can be cut, reheated in the furnace and then reshaped.  This process requires considerable training and patience but is only the beginning of the early technology of making a sandglass!

Next week I’ll talk about how sand wasn’t necessarily sand and how early on the concepts of friction as it relates to the angle of repose were discovered and solved to make these pieces work more reliably!  St. Patrick and St. Brendan don't seem quite as primitive to me now….