auk, an almost complete skeleton of an extinct moa and a large collection of specimens from the Yorkshire region including the remains of elephants, cave bears and hyena from Kirkdale Cave dated to the Quaternary period, around 125,000 years ago. The geological collection contains over 112,500 specimens of rocks, minerals and fossils. Fossils make up most of the collection numbering over 100,000 samples, and include important specimens from the Carboniferous, Mesozoic and Tertiary periods. The archaeology collection has close to a million objects that date from around 500,000 BC to the 20th century, including the Coppergate Helmet discovered in York in 1982, and the Ormside Bowl, an intricate example of an Anglian silversmith. Most of the museum's astronomy collection is housed in the octagonal observatory in the centre of the gardens, built during 1832 and 1833. The design of its rotating roof is credited to John Smeaton designer of the Eddystone Lighthouse. A telescope built in 1850 by the instrument maker Thomas Cooke of York was installed during the observatory's 1981 restoration. It is Yorkshire's oldest working observatory and as of August 2007 was opened to the public by a team of volunteers. The building is currently opened every Thursday and Saturday 11.30 until 2.30. The clock in the observatory was made by Barraud of London in 1811, and during the 19th century it was used to set the time for other clocks in York. At the eastern, Museum Street, entrance to the gardens is Museum Gardens' Lodge built in 1874 to a design by George Fowler Jones in a Victorian Gothic revival style. The lodge now houses the Yorkshire Philosophical Society's offices and reading room. The curator's house ('Manor cottage'), built in 1844 and originally called the keeper's house, is located by King's Manor. It was designed by J B Atkinson and was built using reclaimed limestone from St. Mary's Abbey. Tempest Anderson Hall The Tempest Anderson Hall is a 300-seat auditorium-style lecture theatre built in 1912 as an annexe to the Yorkshire Museum. Dr Tempest Anderson, a York surgeon and vulcanologist, presented the hall to the Yorkshire Philosophical Society to replace its existing lecture theatre. Designed by E. Ridsdale Tate, it is an early example of the use of reinforced concrete and is a Grade I listed building. In the late 20th century it housed a cinema, but it is now used as a conference venue and lecture