H.R.Robinson Helmet Typology

[Caratacus]

I don't think you need an accurate date to classify a helmet as belonging to a certain period of roman history. "Early imperial" for example encompasses enough of a space of time to give a clear idea of when a helmet was used.

Yes, I can see that. I didn't really mean that a given helmet should (or could) be pinned down to just a few years. However, there is obviously often a considerable overlap in use of the various types. Metal was a valuable commodity and a helmet could continue in use many years after its manufacture. We see dates given for Coolus type helmets ranging from the 1st CBC to the 1st CAD and during the second half of this period we are also seeing the so-called "Imperial Gallic" types coming into use. My point was that a date - per se - isn't a useful basis for establishing a typology - when (a) more than one type occupies the same time period or (b) when the period/date of the helmet isn't known with any accuracy. I repeat that a typology must work under all circumstances, not just when we know some of the information in some of the cases. So, if a 'Coolus' and an 'Imperial Gallic' are both dated to the "1st century AD", we can't use "Early Imperial" as a type designation for two helmets that are clearly very different, can we?

Form and decoration, however, seem fairly sensible definers whether of pottery or helmets.

I can tentatively agree with this statement. There are clearly differences in form between the types that Robinson used and within those forms there are also differences in what we might call 'decoration'. I suppose the question arises as to whether a given 'decoration' is of any significance as to a type?

I work on a regular basis with 'samian' pottery (mainly decorated, but also plainware). There are roughly 100 common 'types', which differ as to shape/form (designated by "author-number", e.g. Dr.37, Dr.29, Curle 11). However, once you get past the shape of the pot, you get the decorative features, both figurative and non-fugurative (the latter often abstract) designs. These are described by other authors (e.g. Hermet, Oswald, Rogers, Mees) and there are thousands of the things (literally - around 5,000 all together). These, however, are not 'types' - they are merely used to describe the designs that appear on the vessels. The types are the shapes and these are basically only of one characterstic. When we move on to helmets we have a very different situation. The number of actual types is fairly small (far smaller than the samian types) but the variations within those types leading to sub-types is quite large (have a look at the helmet catalogue page on RAT and you will see how many there are.)

The database you quoted uses the pot shape as a search item (although you can narrow it down by specifying 'decorated' or 'plain' and you can also include a date range, e.g. 'Hadrianic'). Would that we had something like that for helmets!