Figure 6. A thermal image of the two helmets in full sunlight after 10 minutes. Unexpectedly the two helmets exteriors also showed significant variation, the standard helmet at left is already around 60oC at its apex, and is significantly hotter than the right hand helmet over most of its surface. It is starting to merge in with the ambient temperature of the wooden board it stands on (the blue patch in front of it is where I stupidly slid it backwards for the photo and exposed a shaded patch of wood!). The ‘drop liner’ helmet at right remains predominantly in the high 40s low 50oCs, but is starting to heat up at the top. Whether the variation between the two helmets thermal responses is due to the different liners, or whether it’s the difference in heat absorption between the cork shell and the felt shell is not known, although the heating of the front and back of the brim of the left (cork) helmet would suggest it is a factor. The wooden baseboard was exposed to the sun for a long period of time before the helmets were placed on it, so the helmets’ heating is not just solar, but also from the hot surface below. It can be assumed that the longer they stayed in the direct sun, they would probably approach parity. It can also be seen that the puggarees do tend to stay cooler than the shell itself. Traditionally of course the puggaree could be soaked in water and by evaporation help cool the helmet, whether this was done regularly in practice is a question for other researchers. I thought it best not to soak my 103 and 78 year old helmets!