The Seventeenth Century 91 



that their interests should turn to such subjects as heat, fire, light, 

 and color. Well-known students of optical phenomena, like Gas- 

 sendi (1592-1655), Descartes (1596-1650), Kircher (1602-1680), 

 Grimaldi (1618-1663), Boyle (1627-1690), Huygens (1629-1695), 

 Hooke (1635-1703) , and Newton (1642-1727) , lived the productive 

 part of their lives in the seventeenth century, and most of them 

 were familiar with luminescences of all kind. The phraseology and 

 terminology of these men was sufficiently modern for ready compre- 

 hension. Symbolism and mysticism were rapidly disappearing. It 

 is, therefore, appropriate to begin the history of luminescence dur- 

 ing this century with the man most responsible for the change, 

 Francis Bacon (1561-1626) . 



Francis Bacon 



At the beginning of the seventeenth century the distinction be- 

 tween organic and inorganic luminescences was not clearly drawn, 

 but a surprising number of luminous bodies were recognized. The 

 first adequate enumeration of low temperature light emissions is to 

 be found in Francis Bacon's discussion ^ of light, in a manuscript 

 which deals with that subject alone, " Topica Inquisitionis de Luce 

 et Lumine," written before 1612. The first section, which is an 

 excellent example of his approach to natural phenomena, discusses 

 sources of light: 



We have first to note which are the substances, of whatever kind, that 

 generate light; as stars, fiery meteors, flame, wood, metals, and other 

 burning bodies, sugar in scraping or breaking it, the glowworm, the 

 dews [drops] of salt water when it is agitated or scattered, the eyes of 

 certain animals, some sorts of rotten wood, large quantities of snow; 

 perhaps the air itself may possess a weak light adapted to the vision of 

 the animals which see by night; iron and tin, when put into aqua fortis 

 to be dissolved, boil, and without any fire produce intense heat, but 



" Bacon's sources of information were largely Aristotle, Pliny, Albertus Magnus, 

 Jerome Cardan, and Arab writers. His estimation of them in The advancement of 

 learning (1605) is quite frank: ". . . in natural history, we see there hath not been 

 that choice and judgment used as ought to have been; as may appear in the writings 

 of Plinius, Cardanus, Albertus and divers of the Arabians; being fraught with much 

 fabulous matter, a great part not only untried, but notoriously untrue, to the great 

 derogation of the credit of natural philosophy with the grave and sober kind of wits. 

 Wherein the wisdom and integrity of Aristotle is worthy to be observed; that having 

 made so diligent and exquisite a history of living creatures, hath mingled it sparingly 

 with any vain or feigned matter; and yet on the other side hath cast all prodigious 

 narrations which he thought worthy the recording into one book; excellently discern- 

 ing that matter of manifest truth, such whereupon observation and rule was to be 

 built, was not to be mingled or weakened with matter of doubtful credit; and yet 

 again that rarities and reports that seem uncredible are not to be suppressed or denied 

 to the memory of men." 



