CHRISTIAN HUYGENS 69 



Huygens with the interpretation of a writing in cipher.^ 

 Everything almost at which he worked was kept back for 

 a long time; much only appeared after his death from his 

 posthumous papers. 



Huygens was born at the Hague in Holland of a very 

 respected, influential, and well-to-do family, which fact en- 

 sured him for his whole life independence for his work, and 

 enabled him to travel a great deal. He studied together with 

 his brother Constantine, who was a year older, jurisprudence 

 and mathematics at the Hague. His first scientific achieve- 

 ment was mathematical, and connected with his study of 

 Archimedes and Descartes; in it he appears as one of the 

 founders of the calculus of probability, which has since be- 

 come so important for science. His invention of the pen- 

 dulum clock, the first communication concerning which he 

 published in 1667, soon made him widely known. It was 

 astonishing how thoroughly he developed this means of 

 measuring time, which is to-day quite general. His work 

 was almost exhaustive, and developed the clock in all 

 essentials to the form at present in use; he linked with it, in 

 the work Horologium Oscillatorium which appeared in 1673, 

 a further mass of experimental results which went far be- 

 yond the actual subject. 



Huygens' pendulum clock raised the measurement of 

 time, both in science and daily life, almost suddenly to a 

 quite new level of refinement, which had hitherto been 

 striven for in vain, and was hardly imagined as possible. 

 It is true that clocks with hands and trains of wheels driven 

 by weights, had long been in existence, but they went 

 irregularly and unreliably; for they were only regulated by 

 frictional resistance, which is always variable. No great 

 improvement was made when the step was taken of causing 



^ See the life written by P. Zeeman in the memorial to Huygens on the 

 300th anniversary of his birth (1929). There also will be found portraits 

 of Huygens in his youth. 



