{ "cells": [ { "cell_type": "code", "execution_count": 1, "metadata": { "execution": { "iopub.execute_input": "2026-06-23T19:33:13.285927Z", "iopub.status.busy": "2026-06-23T19:33:13.285738Z", "iopub.status.idle": "2026-06-23T19:33:13.289055Z", "shell.execute_reply": "2026-06-23T19:33:13.288662Z" }, "tags": [ "remove-cell" ] }, "outputs": [], "source": [ "# This cell does not render in the docs because it has a `remove-cell` tag.\n", "import warnings\n", "\n", "warnings.filterwarnings(\"ignore\")" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# A chemical map of British Bronze Age axes\n", "\n", "## The Bronze Age in Britain\n", "\n", "Around 2400 BC, metal tools began to appear across the British Isles. Over the next millennium and a half, communities learned to mine copper, to alloy it with tin into the harder, tougher material we call bronze, and to cast that bronze into tools, weapons, and ornaments. This stretch of time, roughly 2400 to 800 BC, is the British Bronze Age. It draws to a close when ironworking takes over.\n", "\n", "Of everything Bronze Age people made, the axe is the most abundant and the most telling. It was the everyday workhorse, used to fell trees, shape timber, and clear ground. But it was also a thing of value: hoarded, exchanged, and sometimes placed deliberately in rivers and bogs. Because axes were made continuously for 1,500 years and their shapes drifted steadily over that time, archaeologists treat them as a kind of clock, where the form of an axe is a rough guide to when it was made.\n", "\n", "Here we ask a simple question. Each axe has a chemical composition, the proportions of metals it contains. If we let UMAP arrange the axes by that composition alone, will the arrangement rediscover the history we already know? And might it show us something we would otherwise miss?" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## How an axe changed over 15 centuries\n", "\n", "The axe did not stay still. The earliest smiths cast a flat or lightly flanged wedge of metal and lashed it to a wooden handle, or haft; the flanges were just low ridges raised along the edges. Over time they raised those flanges higher and added a transverse stop-ridge to keep the haft from splitting, producing the palstave of the middle centuries. Later still they cast a hollow socket directly into the head so the haft could slot inside, giving the socketed axe of the final Bronze Age. The three finds below sketch that journey from left to right, lining up with the three broad ages that organize everything to come: Early, Middle, and Late.\n", "\n", "
| \n", " | ArtefactID | \n", "Cu | \n", "Sn | \n", "As | \n", "Sb | \n", "Pb | \n", "Ag | \n", "Ni | \n", "Fe | \n", "Co | \n", "Bi | \n", "Laboratory | \n", "BasicType | \n", "
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | \n", "96 | \n", "79.10 | \n", "9.6 | \n", "0.30000 | \n", "0.30000 | \n", "8.200000 | \n", "0.30000 | \n", "0.070000 | \n", "0.100000 | \n", "0.000 | \n", "0.120000 | \n", "unknown | \n", "Class 1 | \n", "
| 1 | \n", "148 | \n", "97.00 | \n", "0.0 | \n", "2.30000 | \n", "0.49000 | \n", "0.007000 | \n", "0.28000 | \n", "0.015000 | \n", "0.005000 | \n", "0.007 | \n", "0.005000 | \n", "British Museum | \n", "Class 2 | \n", "
| 2 | \n", "150 | \n", "88.50 | \n", "11.6 | \n", "0.16000 | \n", "0.01000 | \n", "0.090000 | \n", "0.02500 | \n", "0.012000 | \n", "0.000000 | \n", "0.003 | \n", "0.000000 | \n", "British Museum | \n", "Class 4 | \n", "
| 3 | \n", "336 | \n", "99.96 | \n", "0.0 | \n", "0.01000 | \n", "0.02000 | \n", "0.000000 | \n", "0.01000 | \n", "0.010000 | \n", "0.000000 | \n", "0.000 | \n", "0.000000 | \n", "unknown | \n", "Class 2 | \n", "
| 4 | \n", "376 | \n", "100.02 | \n", "0.0 | \n", "0.11465 | \n", "0.19618 | \n", "0.005096 | \n", "0.15121 | \n", "0.009936 | \n", "0.008917 | \n", "0.000 | \n", "0.001274 | \n", "British Museum | \n", "Class 2 | \n", "
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" \"output_notebook(resources=INLINE)\\n\"+\n",
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" \"\\n\"+\n \"BokehJS does not appear to have successfully loaded. If loading BokehJS from CDN, this \\n\"+\n \"may be due to a slow or bad network connection. Possible fixes:\\n\"+\n \"
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