Features:

  1. This is where backyard astronomy ends up if you let it get out of hand.

  2. The Leviathan was built by William Parsons, Lord Rosse, formally 3rd Earl of Rosse (1800-1867)---but I don't think that is Lord Rosse on the platform

  3. It was located at Birr Castle (Lord Rosse's estate) in Birr (formerly Parsonstown), County Offaly, Ireland.

  4. The Leviathan was a reflector with primary mirror of diameter 1.83 meters (72 inches or 6 feet) made of speculum with a mass of nearly 4 metric tons. It took 5 attempts over 3 years (1842--1845) to construct the primary mirror (Wikipdia: Leviathan of Parsonstown: Construction and Design).

    Speculum is an alloy of copper and tin with a dash of arsenic---which gives it that extra kick---invented for reflector telescope mirrors by Isaac Newton (1643--1727).

    It is brittle, tarnishes easily, and reflects only about 16 % of incident visible light.

    By the later 19th century, reflector primary mirrors were made of glass (eventually borosilicate glass: see Wikipedia: Borosilicate glass: optics) with a thin reflective coating first of silver and later of aluminum (Wikipedia: History of the telescope). No more speculum.

  5. The Leviathan could be slewed through a fairly large range in altitude (maybe 10°--170°???), but only ∼ 15° in azimuth centered on the meridian (Wikipdia: Leviathan of Parsonstown: Construction and Design).

    The telescope mount was an altazimuth mount with such limited range in azimuth that was close to a transit mount (Wikipedia: Leviathan of Parsonstown: Side note).

    Astronomical objects could be observed for about an hour centered on their transits of the meridian.

  6. The Leviathan's poor telescope mounting and the cloudy-rainy climate of Ireland greatly limited the utility of the Leviathan, but it was a magnificent cryptid.

  7. The Leviathan was dismantled in 1914. A modern Leviathan reconstruction was build in 1996--1999.

  8. The Leviathan's greatest discovery was the spiral nature of the spiral nebulae which we now call spiral galaxies (Wikipedia: Leviathan of Parsonstown: Operation). The discovery 'twas by Lord Rosse in 1845. For more on Lord Rosse's discovery of the spiral nebulae, see Galaxies file: galaxy_whirlpool_lord_rosse.html.

  9. The Leviathan continued in operation until circa 1890, but its initial discovery of the spiral nebulae was its greatest achievement.

    It is NOT unusual that greatest discoveries are made early on with an new instrument. Whenever a new advanced instrument comes online, it is natural that its new capabilities are used to discover new things very quickly. The new discoveries that are possible are then sometimes exhausted though sometimes NOT as for example with the Hubble Space Telescope (HST, 1990--2040?, d = 2.4 m, Cassegrain reflector).

    https://commons.wikimedia.org/wiki/File:John_Dreyer.gif

  10. Image 2 Caption: Danish-Irish astronomer J.L.E. Dreyer (1852--1926).

  11. Dreyer began his compilation New General Catalogue (NGC) deep-sky objects (most notably galaxies) using the Leviathan in the period 1874---1878. Dreyer made valuable detailed drawings from visual astronomy (No-497): valuable thanks to the rather slow development of astrophotography (advent 1840, but with only gradually improving technique in following decades) (Wikipedia: Astrophotography: History). It may that the Leviathan stopped doing any real research when Dreyer left in 1878.

    Dreyer's New General Catalogue (NGC: 1888) and the Index Catalogue (IC: 1895, 1908) of deep-sky objects include many spiral nebulae. Many nearby galaxies are still known by their NGC numbers or IC numbers.

  12. See the Leviathan / Lord Rosse (1800--1867) videos below (local link / general link: telescope_leviathan_lord_rosse_videos.html).

    EOF