Sachse.] ^^ [Feb. 1, 



two principles; a conclusion arrived at by the space for the stylus 

 on the meridial line, which has been replaced, and the figure upon 

 the rim, which evidently supported the elevated gnomon upon the 

 same line. 



Ozanan, in his J? ecrea/ions (London, 1708), also gives a problem 

 " to describe a dial by refraction." 



The first public mention of, or reference to, the phenomena of the 

 refraction of light was made by Willebrord Snellius (1591-1626), 

 the celebrated mathematician, shortly before his death, or about a 

 half century after it had been practically demonstrated by the 

 Augsburg artificer, as is proven by the specimen here brought to 

 your notice. 



After the death of Snellius, Rene Descartes, by some means, 

 came into possession of the former's experiments on the refraction of 

 light, and published an account of the phenomena, in \\\?> Principia 

 Philosophice, 1637, with several illustrations, from which we may 

 obtain a possible clue to the missing parts once elevated by the 

 figure upon the rim of our interesting specimen. 



Schotus, in his Magia Universalis, published in 1657, also illus- 

 trates the refraction of light, PI. xxiii, by a simple experiment and 

 plate. None of the above references to a refracting dial, or the 

 refraction of light, however, make any reference to the miracle of 

 Isaiah ; thus showing that our scientific relic is unique of its 

 kind, and was known only to persons who were intimately versed 

 in the higher phases of occult philosophy. 



The written records of this venerable Society, so far as I have 

 been able to discover, fail to show just from whom this interesting 

 relic of Christopher Schissler's handiwork was received, or even 

 when it came into possession of the Society. 



Tradition, however, connects this instrument directly with Dr. 

 Christopher Witt, the last surviving member of the Rosicrucian 

 Community, which two hundred years ago was located on the banks 

 of the romantic Wissahickon, in the vicinity of Philadelphia, 

 and usually known as the "Hermits on the Ridge." Dr. Witt, 

 prior to his death in 1765, gave some of his philosophical and 

 scientific apparatus to the local Philosophical Society, then presided 

 over by Benjamin Franklin, among which presumably was the speci- 

 men under discussion. 



It will here again be necessary to take a short retrospect, viz. : 

 Between the years 1 691-1693, a company of religious and philo- 



