The Herschels in this biography are Sir William Herschel (1738-1822), his sister Caroline (1750-1848) and Sir John Herschel (1792-1871), William's son. Sir William was an astronomer and telescope-maker who discovered the planet Uranus in 1781. He was appointed 'the King's astronomer' to George III in 1782, and under his patronage built the then largest telescope in the world. Caroline Herschel worked as her brother's assistant for much of his career but was also an accomplished astronomer in her own right, discovering eight comets and producing a catalogue of nebulae. Her nephew Sir John Herschel was also a distinguished astronomer who made many observations of stars in the southern hemisphere. This book by the astronomer and writer Agnes Clerke (1842-1907), published in 1895, provides both an analysis of their work and an assessment of its contribution to later astronomical research.