Week 4: Ritual Fire Lab Data (Group D)

Introduction

Our group gathered on Mai Fete Island on a windy spring afternoon to investigate early English cremation rites. We burned a pork shoulder (our stand-in body) to test at what temperature the flesh would burn away, and to assess whether placing bodies on or under the funeral pyres is more successful (competing arguments proposed by Calvin Wells and Jackie McKinley). In addition to the tangible things we were after, we payed close attention to our own experiences watching the cremation in order to have a holistic understanding of the ancient ritual. Our procedure had five main stages:

1. Building the woodpile
2. Preparing and placing the “body”
3. Lighting the fire (and possibly tending to it)
4. Retrieving the bone from the ash
5. Placing the bone in an urn

Data Summary

1. Building the woodpile took 18 minutes. We dug a channel underneath the base of the logs to promote air circulation. We knew it worked because when the wind blew we could see the embers catching. The base was 6 logs across. Our partner group placed their body directly on the ground while ours went on top of 3 layers of logs laid in a grid. We filled the gaps in the logs with brush and small twigs from the surrounding area.

2. The pork shoulder weighed 4.73 kg at the start. We laid out a linen napkin and placed the shoulder, skin down (to emulate a person’s back), and then folded the four corners of the linen in and pinned it close with a brooch. We placed our body on top of the pyre and then we added thick sticks (2 in. diameter) upright around the base of the fire, creating a teepee shape. When complete, the pyre measured 135-140 cm across in all directions.

3. At 2:35 PM we lit the fire from the top of the structure with a small clump of brush. The fire was slow to catch. We could hear dramatic popping and crackling sounds from the resin. By 2:38 PM there was some smoke, and at 2:44 PM we used a little bit of paper to boost the flames. At 2:47 PM significant flames arose, and at 2:48 PM the flames leapt to double the height of the wooden pyre, reaching at least 8 ft in the air. Our group stepped back 10 ft to observe. From 10 ft away the fire still warmed our cheeks. At 2:50 PM the flames were neon orange at the center and a darker brown around the edges. The fire temperature cleared 815 °C, signaling that we had a chance of burning away our body and leaving only bone. The sticks completely blackened, but four minutes later at 2:54 PM they had begun to turn light grey and ashy. As the sticks burned down, our body became visible, although we couldn’t tell what the blackened mass was—it was hard to tell if the linen was still there. At 3:13 PM due to the collapse of the sticks our body fell out of the fire and Austin placed it back in. At this point the body was charred with golden brown cracks of exposed flesh that oozed a bubbling liquid. We all agreed it was unpleasant to watch the body decompose and we wished it had remained covered by the linen and fire. Though the fire smelled normal to us, turkey vultures circled overhead. By 4:25 PM the pyre was mostly white ash. We could clearly see the white bone sticking out of one side of our body. At 4:35 PM, the body was the only part of the fire that was letting off smoke. We took the temperature of the body at regular 5 minute intervals. Here is a chart with those results:

Time	Time Elapsed (Minutes)	Body Temp. (°C)	Fire Temp. (°C)
2:35 PM	0	6.3
2:40 PM	5	75
2:48 PM	13	542	465
2:50 PM	15	618.6	719
2:55 PM	20	598, 656
3:00 PM	25	289, 395
3:05 PM	30	242, 282, 322
3:10 PM	35	203, 247, 159
3:15 PM	40	383, 168, 542
3:20 PM	45	319, 168, 542
3:25 PM	50	653
3:30 PM	55	108, 113, 276
3:35 PM	60	472, 526
3:40 PM	65	452, 499
3:45 PM	70	655, 500, 668
3:50 PM	75	108, 113, 276
3:55 PM	80	468, 238, 503
4:00 PM	85	152, 209, 176
4:05 PM	90	132, 121, 221
4:10 PM	95	96, 120, 80
4:15 PM	100	116, 128, 149
4:20 PM	105	156, 95, 118
4:25 PM	110	84, 69, 69
4:30 PM	115	73, 68, 168
4:35 PM	120	84 (top of body) 110 (middle of body)	400 (below body)
4:40 PM	125	67, 65
4:45 PM	130	79 (top of body) 380 (bottom of body)

4. When the fire died out close to the end of lab, we could tell our bodies needed more time in the heat. We decided to leave the site as it was and to excavate it the next day, knowing that it could be tampered with and that it was going to rain overnight. When we returned to the site we could tell our body had been moved, but it was still intact.

5. We placed the body in a red plastic bowl and carried it back to our classroom. The bowl with the body (the remaining ash and bone and flesh) weighed 1181 g, and the bowl alone weighed 158 g, meaning the remains weighed 1023 g. The body lost 3707 g in the cremation process. The exposed white bone matched the 900-1000 °C°C color on the classroom chart that showed the color of bones burned at a range of temperatures. The bottom side of the body was darker and matched the 500-700 °C color range. The body smelled like burnt flesh and a bittersweet mixture of caramelized meat and carbonized matter.

Conclusion

Our body did not fully cremate. While we did have 2 inches of exposed bone, the goal was to have only fragments of bone, and there was still browned meat left on the body as well as a few traces of linen. Interestingly, the metal brooches were lost. The range in bone color at the end shows that our body burned unevenly. The data in our body temperature chart also shows this uneven burning. The person who used the temperature gun took wildly different temperatures of our body, leading us to take the temperature of the body three times later on in the lab. If we had positioned the the blue laser thermometer in the same place it would have led to more accurate and consistent data. Furthermore, we found that the bottom of the body was at a much higher temperature than the top. Our body burned more evenly on top of the pyre than the other group’s body underneath it, leading us to agree with McKinley’s theory. The viewing experience was theatrical during the height of the flames, but the excitement subsided as the fire collapsed. We suggest repeating this experiment in the evening.

• 

• 

• 

• 

• 

• 

• 

• 

•