Density of fallen ash after the eruption of Tambora in 1815

A reassessment of the ash density associated with the eruption of the volcano Tambora, Indonesia, in 1815 is presented by examining contemporary reports. This eruption produced the largest known ashfall in historical times. The density of the fallen ash at Makassar, about 380 km north of Tambora, can be safely stated to be 636 kg m−3.