Illustration of the Whirlpool Galaxy (M51, NGC 5194) made by William Parsons the third Earl of Rosse (1800-1867). Rosse, an Irish astronomer and telescope builder, made this illustration by using a giant reflecting telescope which he built and that became known as the Leviathan of Corkstown". The telescope was 15m long and had a primary mirror with a diameter of 1.8m. With this instrument he was the first to recognise the spiral shape of some fifteen nebulae, including M51. This illustration was taken from a paper written by Rosse which was published in 1850 and entitled "Observations on the Nebulae"."