Glass Identification - Post here for all ID requests > Glass
Units of Measurement
Bernard C:
It seems to me to be reasonable to use as your primary unit of length the unit that was in use by that glassworks at the time, with an alternative measure given in brackets for those of us today who are not used to the system. So, for example, all British glass other than the most modern should be measured in inches, with a metric measurement given as an alternative if it could be useful to some readers, thus:- 8" (20cm). This provides the link to measurements in contemporary material such as pattern books, trade catalogues and advertisements.
It also keeps us well away from loony statements like "The Davidson Column Vase was made in three sizes, 15cm, 20cm and 25.5cm", when we all know it wasn't, it was made in 6", 8", and 10" sizes, and only serves to confirm that the writer is very confused, a complete plonker, or (in Britain) a trained archaeologist*, or, quite possibly, all three.
You can go one step further and use italics to show derived lengths rather than measured lengths, so 8" (20cm) would show that the object was measured in metric only, and that the inch measurement was derived.
So, my question is what primary measurement system should I use for Venetian glass dating from c. 1895–1920? Were the Murano glassworks using the metric system then, or some earlier system? It seems logical to describe the height of my blue vase as 13.5cm (5¼"), but I could be technically incorrect.
In a more general sense, when did the metric system become widely accepted and used on the European mainland? ... and what systems did it replace?
Bernard C. 8)
* — Some years ago I saw the following written by an eminent archaeologist:
"Milestones are found along the road at intervals of 1610 metres".
Hard to believe, but it's true!
Della:
Hello Bernard,
I found this:
http://www.unc.edu/~rowlett/units/metric.html
It has some fantastic history about when the metric system was introduced. I am not sure, if they say which system was in place before this time, as I don't have time to read the whole article, as I am in a hurry to get packed etc.
Whilst I am in the UK, I will try to get a tape measure which has inches on it. I only have a cm tape, as that is what is for sale here in The Netherlands. Although, not knowing where a piece originates from, could cause problems for me :oops:
Which unit of measurement do I use first and which do I put in brackets or italics?
Bernard C:
--- Quote from: "Deltab" ---... Which unit of measurement do I use first and which do I put in brackets or italics?
--- End quote ---
Always the units that the glass was made in first, with other measures in brackets.
Thanks for the link. It shows that Italy was fully metric by the time my glass was made, so the height of my blue vase is quite properly given as 13.5cm (5¼") or just 13.5cm. Note that 13.5cm (5.25") is not correct, as it implies an unwarranted degree of precision, one of the two major problems of the metric system, the other being the relative scarcity of factors of 10 compared to 12.
Bernard C. 8)
Bernard C:
Oh, and don't take me too seriously. If you are measuring a piece for IDing, whatever units of measurement suit you. If you know its origin and age, then it's best to stick to the above guidelines.
Bernard C. 8)
Glen:
I think there are some other things to consider when giving measurements. Essentially I agree with you Bernard, one should use the units of length given by the manufacturing company.
However, I feel there are circumstances when a conversion is justified. Firstly, if the item(s) in question is already well known and sizes are accepted and in common use. For example, if say, a vase is well known as being a 6" vase - then it seems preferable to me to continue referring to it as such, even though the original maker sized it in centimetres.
Secondly, I think it depends on the "audience". I personally prefer (if am writing for a USA audience) to use the Imperial terms, for items made in mainland Europe. If circumstances warrant it, I would also use the original metric measurement.
Glen
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