stretch of the River Wharfe on the Devonshires' Bolton Abbey estate, where the river is pressed into a turbulent chasm just a yard wide. Chatsworth's Strid is a placid stretch of water fringed with rocks and luxuriant vegetation and crossed by a rustic bridge. The Arboretum and Pinetum: The 6th Duke's time was one of plant-hunting expeditions, with major new species readily discovered by intrepid botanists, and the Duke among the most generous sponsors. In 1829 he took an additional of the park into the garden to create a pinetum, and in 1835 Paxton began work on an arboretum planned as a systematic succession of trees in accordance with botanical classification. Chatsworth has some of the oldest UK specimens of species such as Douglas fir and Giant Sequoia. Also in this part of the garden is the Grotto Pond, originally a fishpond, breeding fish for Chatsworth's table. The 6th Duke's mother had the rustic grotto built at the end of the 18th century. The area round the pond is now planted for autumn colour. The Azalea Dell and the Ravine: Rhododendrons and Azaleas grow well at Chatsworth as the soil suits them, and a section of the southern end of the garden is devoted to them. This is the most rugged part of the garden, with steep serpentine paths and a stream running down a valley known as The Ravine. In 1997 a waterfall was created out of old drinking troughs gathered from fields on the estate. There is also a bamboo walk. The Emperor Fountain: In 1843 Tsar Nicholas I of Russia informed the Duke that he was likely to visit Chatsworth the following year. In anticipation of this Imperial visit, the Duke decided to construct the world's tallest fountain, and set Paxton to work to build it. An lake was dug on the moors above the house to supply the natural water pressure. The work was finished in just six months, continuing at night by the light of flares, and the resulting water jet is on record as reaching a height of . However, the Tsar died in 1855 and never saw the fountain. Due to a limited supply of water, the fountain usually runs on partial power, reaching half its full height. The water power found a practical use generating Chatsworth's electricity from 1893 to 1936. The house was then connected to the mains, and a new