A Tuchemeter is a device that measures all the luck in the world. First introduced to the twins in the first book, it shows the luck to be in good, bad, or in homeostasis. Nimrod owns one in his house, a replica of the Blue Djinn of Babylon's official record count- the Berlin Meridian Luck.
In the Akhenaten Adventure, Nimrod started being concerned about the tuchemeter pointing to the left side, the side of evil, so he tried to intervene. By obtaining the allegiance of the Seventy Lost Djinn of Akhenaten, it greatly reversed the direction of the tuchemeter. His own personal tuchemeter, guarded by Creemy, has it own room in his house in London. If the luck tilts too much to the bad site, Creemy raises the alarm and the other good djinn may intervene.
When Moo first sees the tuchemeter, she is amazed but also concerned because the tuchemeters may have be showing false readings. To test this, he had Moo roll dice several times to see if her bad luck would affect the readings so close to the tuchemeter. After her luck falls short of what is expected yet it shows no change Nimrod definitely agrees something is wrong. Later Nimrod discovers the animadvetos may not be working and were not sending the correct readings.