Uylenbroek, Oratio de fratribus Christiano atque Constantino Hugenio (Groningen, 1838); P. Harting, Christiaan Huygens in zijn Leven en Werken geschetzt (Groningen, 1868); J.
Before the close of 1610 the memorable cycle of discoveries begun in the previous year was completed by the observation of the ansated or, as it appeared to Galileo, triple form of Saturn (the ring-formation was first recognized by Christiaan Huygens in 1655), of the phases of Venus, and of the spots upon the sun.
In April 1900 it was successfully defended against the Boers under Christiaan de Wet by a Cape force of Irregulars commanded by Colonel E.
It was further investigated by John Wallis, Christiaan Huygens (who determined the length of any arc in 1657), and Pierre de Fermat (who evaluated the area between the curve and its asymptote in 1661).
The mechanical properties of the cycloid were investigated by Christiaan Huygens, who proved the curve to be tautochronous.
The improvement of telescopes was prosecuted by Christiaan Huygens from 1655, and promptly led to his discoveries of the sixth Saturnian moon, of the true shape of the Saturnian appendages, and of the multiple character of Huygens.