154 History of Luminescence 



teur as well. He wrote Letters on China and was an intimate of 

 Voltaire (1694-1778) , who mentioned him in the satirical poem, 

 Le Temple du Gout (1733) .* 



It is probable that de Mairan's early interest in luminescence led 

 him to prepare another work, Traite Physique et Historique de 

 I'Aurore Boreale, first published in 1733. His views on this celes- 

 tial luminescence, attributed to the atmosphere of the sun descend- 

 ing at times to the earth, were radically different from those ex- 

 pressed in Des Phosphores et des Noctiluques. Details of his remarks 

 on the aurora borealis will be found in Chapter VII on electro- 

 luminescence. 



JOHANN HEINRICH COHAUSEN 



A longer essay,^ and possibly a competitor for the prize, was 

 published by the official physician of the episcopal bishopric of 

 Miinster, Johann Heinrich Cohausen (1665-1750). It was entitled 

 Lumen Novum Phosphoris Accensum,, sive de causa lucis in phos- 

 phoris tam naturalibus, quam artificialihus, Amstelodami, 1717 (see 

 title page in figure 16) . This extensive monograph of 342 pages 

 considered most of the known luminescences and marshalled a con- 

 siderable array of facts. Cohausen's idea of classification is revealed 

 in the table of contents. The book is divided into three parts. The 

 first part, dealing with natural phosphors, has two sections, one 

 treating phosphors of the air (" De Meteoris Lucidus et Igneis ") , 

 the sea (" De Lumine Maris ") and of the land (" De Phosphoris 

 Mineralium, Lapidium et Gemmarum ") , the second with lumines- 

 cence of animals (including man and brutes, animals which see at 

 night, i. e., whose eyes are phosphori, and insects) and plants (in- 

 cluding herbs, roots, and rotten wood) . 



The second part is also divided into two sections. The first section 

 takes up phosphors made artificially, like the Bononian stone, the 



* The poem poked fun at French literature, especially at the poet, Jean Baptiste 

 Rousseau (1670-1741) , who had criticized Voltaire. Concerning the gifted Bernard de 

 Bovier de Fontanelle (1657-1757) , who preceded de Mairan as perpetual secretary of 

 the Academy of Sciences and was also a member of the French Academy of Inscrip- 

 tions, Voltaire wrote: 



" He from a planet came post-haste 



Back to the sacred shrine of Taste; 



Reasoned with Mairan, with Quinault 



Trifeled away an hour or so; 



And managed with an equal skill 



The lyre, the compass and the quill." 

 From the translation of Voltaire's Works 36: 53, Paris, London, New York, Chicago, 

 E. R. DuMont, 1901. 



^Regarded as better than de Mairan's essay by Ehrenberg (1834) but valueless 

 according to Kayser (1908) . 



