The Seventeenth Century 135 



As to the animate, ' tis evident that our English Glow-iuormes, as well 

 as the American, or flaming flyes, have a luminous juice in their tailes 

 which shines in the dark: And 'tis as certain if we may believe the 

 learned Monsieur Auzout, that the clammy moisture of Oysters that 

 shines in the dark of a violet colour, comes from luciferoiis wormes that 

 have their holes in the shells, whereof he distinguishes no less than three 

 sorts [Phil. Trans. 12: 204, 1666]. 



It is true also, as 'tis a common experiment, that a cat rub'd upon 

 the back in the dark against the hair sends forth luminous sparks. And 

 there is a Master of Arts in this University that when He shifts Himself, 

 emits such sparks so violently that they have been heard to crackle like 

 the sparks of fire: all of which (with other instances that might be 

 brought) seem mightily to confirme that there are such accensions, or 

 Platonic flames in the juices of Animals, which shine only, and doe not 

 burn, as were hinted and proved, from the Aerial Noctiluca, and solid 

 Phosphorus. . . . And as for the inanimate luciferous bodies, beside the 

 Bononian and Balduinian stones; the Phosphori, Smagdarinus and Ful- 

 gurans, and of Dr. Kunkelius. Everybody knows that rotten wood and 

 loaf sugar scraped, shine in the dark, and that the salt water of the Sea, 

 more especially when the wind is South East, . . . gives so great a light, 

 that being dashed with Oars, it seem to run off them, just like liquid- 

 flre; . . . 



Now though it be possible indeed that there may be small subterranean 

 Animals, such as Oyster worms etc that may be bred and live in such 

 black, bituminous, moist, rotten earths, or the mud of ditches, and upon 

 sudden commotions may send forth such lights as were at large above 

 mention'd; Yet me thinks they may rather proceed from some salino- 

 sulphurous mixtures that may be in those Earths and Mud, which being 

 smartly moved as in the ditch, or violently striken with the Horses feet, 

 as the Sea-water with Oars . . . may more likely occasion such lights from 

 the same principles (howsoever they operate) as in the salt-iuater of the 

 Sea, though others may more probably think . . . that they may become 

 luciferous by the same means that rotten-wood and stinking fish are so: 

 which yet shine not so much upon account of their rottenness as they doe 

 of their moisture. 



Plot was initially correct in suggesting that the light of the moor 

 might be due to " worms." It is unfortunate that he finally changed 

 his view in favor of " moistine," but the idea that there is light in 

 water was very strong at the time. 



PAOLO CASATI 



Another learned writer on luminescence was the Italian Jesuit, 

 Paolo Casati (1617-1707), teacher of mathematics and theology at 

 Rome, who later became rector of the College in Parma. He wrote 

 a number of works on physics, dealing with mechanics, hydrostatics. 



