Darwin's interest in the fertilisation of orchids led him to get a new heated greenhouse constructed under the supervision of John Horwood, the gardener of Mr Turnbull at The Rookery: this was completed in February 1863. It includes a tunnel passageway that allows bees to fly in and out. In 1872, a verandah was added to the west side of the new drawing room, and in 1877, a new billiard room was added to the east of this block, with the hallway being extended to form a new entrance hall and Georgian-style porch facing east. The new billiard room was converted to a new study in 1881, and the old study where Darwin wrote "On the Origin of Species" was converted into a smoking room. In the same year, Darwin bought a strip of land to the north of the property, beyond his orchard, and had a hard tennis court and a new wall built.