98 History of Luminescence 



1680) , the Cartesian doctrines were well defended, but only 

 LeGrand among the three discoursed at any length on lumines- 

 cences, expressing opinions which will be considered in a subse- 

 quent section of this chapter. Descartes's son-in-law, the physicist 

 Jacques Rohault (1620-1675) , and the chemist Nicolas Lemery 

 (1645-1715) were likewise Cartesians. Their views on luminescence 

 will be presented in final sections of this chapter. 



In later years of the seventeenth century, theories of light were 

 chiefly two, the wave " theory of Robert Hooke (1635-1703) and of 

 Christian Huygens (1629-1695) , opposed by the corpuscular^* theory 

 associated with Isaac Newton. It should be pointed out that even 

 those scientists who compared the propagation of light to a wave 

 motion, nevertheless regarded the generation of light as connected 

 with movement of particles. Newton's influence and authority were 

 so great that, despite the contrary views of Descartes, of Hooke and 

 Huygens, the conception of light as a material substance persisted 

 throughout the eighteenth century. Although Leonard Euler (1707- 

 1783) supported the wave theory in his Nova Theoria Lucis et 

 Colorum, etc. (Berlin, 1746) , his views were not generally accepted,^^ 

 and it was the work of Thomas Young (1773-1829) , supported by 

 that of Augustin Fresnel (1788-1827) which finally led to abandon- 

 ment of the corpuscular theory during the nineteenth century. 



Scientific Societies and Luminescence 



With increasing interest in physical phenomena of all kinds, it 

 was natural for those concerned to meet togther for mutual discus- 

 sion. The trend began in the sixteenth century in Italy.^^ The 

 earliest of such gatherings and the forerunner of stable societies was 



^* Franchesco Maria Grimaldi (1618-1663) of Bologna, the discoverer of diffraction, 

 thought of light as a wave. He did not study luminescence except to explain the blue 

 color of " lignum nephriticum " extract (actually a fluorescence) as a reflection of 

 light (see Chapter XI) . 



^* In discussing sight, Thomas Willis (1621-1675) , in his Exercitatione duae de anima 

 brutorum (London, 1672, Chap. XV) leaned toward the view that light consists "of 

 most thin little bodies," but had difficulty in understanding how they could move so 

 rapidly, " for when a candle being lighted, immediately the whole chamber is illumi- 

 nated, it can scarse be conceived, that the fiery little Bodies of that flame, should 

 break forth so suddenly or so thick, that they should fill, in the twink of an Eye, so 

 vast a space. . . . Besides, when from a glow-worm, a certain Kind of Light or fire 

 shines in the dark, and is perceived at a distance, if this apparition should be made 

 by reason of the fiery little Bodies streaming from this little Creature, whence I pray 

 is so much fiery Tinder supplied? . . ." (from the translation. Two discourses con- 

 cerning the soul of brutes, London, 1683, p. 75) . 



^^ See chapter VIII on Phosphorescence for Euler's views on phosphors, on color, 

 and on reflection of light. 



*• See Martha Ornstein, The role of scientific societies in the 17th century, Univ. of 

 Chicago Press, 1928. 



