Fifteenth and Sixteenth Centuries 89 



but its explanation remained wholly obscure. Among inorganic 

 luminescences the stories chiefly concerned luminous gems. The 

 Bolognian phosphor had not yet been discovered, and nearly a cen- 

 tury must elapse before the element phosphorus would become 

 available to those who could afford it. Nevertheless, many facts 

 had been accumulated. The scene was set for the great investigators 

 of the seventeenth century and the start of Science as known today. 



The end of the sixteenth century, the time of Shakespeare (1564- 

 1616) and Queen Elizabeth (1558-1603), of Sir Walter Raleigh 

 (1552-1618) and the Spanish Armada, is also famous for the names 

 of William Gilbert of Colchester (1540-1603), physician to Queen 

 Elizabeth, Francis Bacon, Baron Verulam (1561-1626) , and Galileo 

 Galilei (1564-1652) . All three men adopted the scientific method. 

 Neither Galileo nor Gilbert studied luminescence although each 

 became leaders in their field. Gilbert's De Magnete (1600) marks 

 the beginning of research in magnetism and electrical attraction, and 

 Galileo's studies cover many fields. 



Of the three men. Bacon paid most attention to luminescence. 

 Like Galileo, Bacon actually bridges the two centuries. Although 

 born in the sixteenth and endowed with a spirit of intellectual re- 

 volt, his early life was so unstable that only in the seventeenth cen- 

 tury did he have the leisure to set down his ideas in writing. Bacon's 

 many remarks on luminescence will make a fitting beginning for 

 the seventeenth century which was to see the investigation of lumi- 

 nescences carried on in an extensive and logical manner. 



