Brooches of the late Iron Age and Roman period
The only comprehensive classification of late Iron Age and Roman brooches is Mackreth 2011 , which is now out of print. Other books, such as Bayley and Butcher 2004 , and Hattatt's volumes (including the Visual Catalogue, Hattatt 2000 ) are useful sources of parallels and common names for brooch types. Plouviez 2008 sets out periods to which brooch types can be allocated, in a similar way to Reece's coin periods.
The parts of a late Iron Age or Roman brooch
Late Iron Age and early Roman brooches are all bow brooches; plate brooches come back into fashion at the end of the first century AD. Bow brooches can be sprung, or hinged. A spring is made from wire, and has a number of coils, which start to one side of the pin and wind outwards. When the end of the spring has been reached, the wire is taken across the spring to start winding again at the far end, coiling inwards towards the pin. When counting the number of coils, count them from the reverse, and include the final one that continues downwards to form the pin. A chord can be internal (running across below the spring, inside the space enclosed by bow and pin) or external (running across above the spring, outside the space enclosed by bow and pin).
Some of the most common and popular types of Romano-British brooch as classified by the PAS are as follows:
Aucissa brooches, have hinged pins held in a narrow tube formed from rolling the top of the head up and forwards, and cutting a slot for the pin. Many have decoration on the head, some with the stamped name AVCISSA and others with dots or zig-zags. The bow is highly arched and generally has bold longitudinal ridges and grooves. The foot is generally undecorated except for a footknob.
The Colchester brooch always has a forward-facing hook to hold the (external) chord. They are often called 'Colchester one-piece' brooches, and most of the brooch was indeed made out of a single piece of metal, but they can have a separate axis bar. Colchester brooches normally have small rectangular-section undecorated wings, a relatively long hook and a slim, undecorated bow. Early Colchester brooches can have nearly straight bows; late ones can have decoration on the bow and sometimes on the catchplate. Some were made on the Continent and imported; diagnostic features for these include a faceted cross-section to the bow, and a short hook. Colchesters are often so corroded that detail is lost.
These look like Colchester brooches, but have chunkier proportions. The wings are normally curved in cross-section and the bows taper from a thick hump at the top to a pointed foot. They were once called 'dolphin' brooches, but are now divided into several types on the basis of their pin fixings.
A common form of Colchester derivative, the Polden Hill is defined by having the axis bar held at each end. This is normally by means of a pierced circular plate at the outer end of each wing (often called 'wing caps'), but there is also a group of brooches (Mackreth's 'Eastern Group', CD PH 6), where the wing ends are formed into short cylinders. Fixing the axis bar, spring and pin in this way was more secure than the other Colchester Derivative methods. There is often also a way of securing the chord; this is normally either held by a pierced lug or crest on the top of the head (like the Harlow), or a rear-facing hook in the centre (like the rearhook). Very occasionally one is found with a forward-facing hook on top of the head (like the Colchester). Both Mackreth (2011, 69) and Bayley and Butcher (2004, 89) define all brooches with pierced plates at the ends of the wings as Polden Hill, whether they have a rear-facing hook in the centre, or a pierced lug in the centre, or no method of holding the chord, and the PAS follows this system. It may turn out that the method of fixing the chord is important, though, so check that you have examined and described it.
A crossbow brooch is probably named from having wide wings that form a cross at the top of the bow, because it doesn't look much like a medieval crossbow. Crossbow brooches also have a highly arched bow, and a fairly long foot which has a narrow catchplate running down its whole length. Crossbows have hinged pins (sprung versions are proto-crossbows) and three knobs, one (the top knob) in the centre of the head and two (the side knobs) at the ends of the wings. Proto-crossbow brooches are classified separately, and are very variable. If you can't tell whether you are dealing with a crossbow or a proto-crossbow (perhaps because you just have a fragment of foot) then leave the Classification field blank, and give details in the Description field.
It is unlikely that you will mix up a dragonesque brooch with any other brooch type. They are very distinctive, S-shaped and with the pin looped around one terminal and secured against the other (so with no catchplate). The way of fastening the pin is not like any plate or bow brooch; it is most like a penannular brooch. Hunter (2011) has looked at the decoration on dragonesque brooches and has proposed a classification based on the presence or absence of enamel, so look closely for evidence of this.
The stud that names this group is below the wings, and could be described as being at the top of the bow. This is an eclectic group with plenty of variable decoration, and the stud can be replaced by a simple moulded decoration, a crest, a dog, a plain enamelled cell or a double stud. Headstuds also have a variety of pin arrangements, some sprung and some hinged. The sprung varieties can have the chord held by a forward-facing hook, or a rear-facing hook, or a pierced lug on the top of the head; the axis bar is held by a pierced lug in the centre of the wings. The hinged varieties have an axis bar mounted in a tube fitted behind the wings.
Hod Hills have hinged pins held in a narrow tube formed from rolling the top of the head up and forwards, and cutting a slot for the pin. The axis bar is normally of iron. The bow is divided into an upper and a lower part; the upper bow is often wider, normally vertically ribbed, and can have a pair of side knobs projecting from top, centre or base. The lower bow is usually narrower, flatter and minimally decorated, and with a small footknob. Many (perhaps most originally) have a white-metal coating.
Knee brooches resemble a bent knee, and as the foot is often bent forwards they can look very like a leg from Georgian or Victorian furniture. They can have rounded heads or semi-cylindrical wings, and the pins can be sprung or hinged. Some have a small headloop, some have enamelled decoration.
The classic Langton Down has wings in the form of a thin sheet cylinder with a seam along the reverse and a slot in the centre for the pin. The bow is broad and tapers only slightly; it is usually decorated with wide vertical grooves. The Nertomarus type has distinctive relief decoration on the head (use the word 'Nertomarus' in the Description field.
These are defined as having an open circular frame. The open ends have terminals, which can be hard to describe. A brooch with terminals that are in the 'same plane' as the frame will essentially be flat; terminals at right angles to the frame of the brooch will stick up at right angles.
Rosette brooches have wings in the form of a thin sheet cylinder with a seam along the reverse and a slot in the centre for the pin. They look like Langton Down brooches but have a large plate in the centre, usually circular, sometimes lozengiform. Some early examples have the forward-facing hook of the Colchester. Some late ones have hinged pins and have become very flat, and are often called 'keyhole' brooches (put 'keyhole' in the Description field).
A 'trumpet head' (which can be found on many other types of brooch) is solid and in the shape of a concave-sided cone, like the bell of a trumpet (or other brass instrument). They normally flare to an oval shape, but it can also be nearly rectangular or nearly circular. The trumpet heads often have a bordering groove. This 'mainstream trumpet' or 'standard trumpet', (Mackreth's type 1) has a trumpet head with sprung pin. The spring is mounted on a single central vertical lug behind the head, with a wide piercing for the axis bar. The axis bar often continues up to form a headloop with a separate collar, and a little projection at the top centre of the head serves to restrict the movement of the headloop and collar. The bow of a classic trumpet brooch has a 'knop'. This typically consists of a single central transverse ridge, with 'petals' above and below. Count the petals if you can. Use the term 'petals' (or 'petal knop' for both petals and central ridge) rather than 'acanthus', which is hard to understand. Above and below the petalled knop are further transverse ridges. Check whether the knop mouldings run all the way around the bow (full-round) or just on the front, with a flat reverse (half-round). The lower bow usually has a central ridge or arris, often with a groove down each side, and tapers before ending in a footknob.