In the 17th and 18th centuries, tea leaves were so valuable that they were kept inside a locked container known as a tea chest. This chest, which is made from tortoiseshell, contains a pair of canisters for green and black tea and a central box for mixing a blend of both types of tea or for sugar. As the 18th century progressed, tea canisters became known as tea caddies. The term caddy derives from the Malay word, kati: a unit of measurement used for weighing tea. The kati was equivalent to about 1-1/3 pounds (600 grams), the amount in a standard 18th century packet of tea. The shape of this tea chest, which combines a classical rectilinear form with curvaceous rococo features, was very common in the 18th century. Similar designs for tea chests can be seen in the third edition of Thomas Chippendale’s Director, a furniture pattern book published in 1762. Each component in this set is set with silver engraved with the armorial crests and monograms of John Lyall whose son George went on to become the Chairman of the East India Company.