This instrument is a recorder for determining distance travelled and therefore ship Inchess speed. It is made of brass with a ceramic dial, with the main scale marked from 0 to 100 miles and two inset dials marked from 0 to 1000 miles and 0 to 1 mile. It has a fixing plate, on which it can turn, with which it would have been attached to a suitable part of the ship, typically the taffrail, the rail at the stern of a ship. As a result, this type of log was often called a taffrail log. The recorder would have been connected to a rotor that was towed behind the ship. The revolutions of the rotor registered on the indicator, thus measuring the distance travelled. For this model, 900 revolutions of the rotor registered as 1 nautical mile.

Thomas Ferdinand Walker (1837 Inches1921) first patented the Cherub log in 1878. It was one of the first logs in which the recorder was placed on board the ship rather than being part of the rotor.

This example includes the spinner and the governor making it very complete. With clear marks on the face and engraved on the log: "Walker Cherub Log Mark III Trademark, With an anchor with the initials T.W. underneath, Made in England by Thomas Walker and Son Ltd., 58 Oxford St., Birmingham. Use Walker’s solidified oil." There is a log of this type in the Royal Maritime Museum, Greenwich but without the spinner and governor.