This was his last work, for after a long illness he died at Bonn on the 1st of January 1894. By his premature death science lost one of her most promising disciples. Helmholtz thought him the one of all his pupils who had penetrated farthest into his own circle of scientific thought, and looked to him with the greatest confidence for the further extension and development of his work. Hertz's scientific papers were translated into English by Professor D. E. Jones, and published in three volumes: _Electric Waves_ (1893), _Miscellaneous Papers_ (1896), and _Principles of Mechanics_ (1899). The preface contributed to the first of these by Lord Kelvin, and the introductions to the second and third by Professors P. E. A. Lenard and Helmholtz, contain many biographical details, together with statements of the scope and significance of his investigations. HERTZ, HENRIK (1797-1870), Danish poet, was born of Jewish parents in Copenhagen on the 25th of August 1798. In 1817 he was sent to the university. His father died in his infancy, and the family property was destroyed in the bombardment of 1807. The boy was brought up by his relative, M. L. Nathanson, a well-known newspaper editor. Young Hertz passed his examination in law in 1825. But his taste was all for polite literature, and in 1826-1827 two plays of his were produced, _Mr Burchardt and his Family_ and _Love and Policy_; in 1828 followed the comedy of _Flyttedagen_. In 1830 he brought out what was a complete novelty in Danish literature, a comedy in rhymed verse, _Amor's Strokes of Genius_. In the same year Hertz published anonymously _Gengangerbrevene_, or Letters from a Ghost, which he pretended were written by Baggesen, who had died in 1826. The book was written in defence of J. L. Heiberg, and was full of satirical humour and fine critical insight. Its success was overwhelming; but Hertz preserved his anonymity, and the secret was not known until many years later. In 1832 he published a didactic poem, _Nature and Art_, and _Four Poetical Epistles_. _A Day on the Island of Als_ was his next comedy, followed in 1835 by _The Only Fault_. Hertz passed through Germany and Switzerland into Italy in 1833; he spent the winter there, and returned the following autumn through France to Denmark. In 1836 his comedy of _The Savings Bank_ enjoyed a great success. But it was not till 1837 that he gave the full measure of his genius in the romantic national drama of _Svend Dyrings Hus_, a beautiful and original piece. His historical tragedy _Valdemar Atterdag_ was not so well received in 1839; but in 1845 he achieved an immense success with his lyrical drama _Kong Rene's Datter_ (King Rene's Daughter), which has been translated into almost every European language. To this succeeded the tragedy of _Ninon_ in 1848, the romantic comedy of _Tonietta_ in 1849, _A Sacrifice_ in 1853, _The Youngest_ in 1854. His lyrical poems appeared in successive collections, dated 1832, 1840 and 1844.