The Seventeenth Century 141 



and so produce the light." The details of his ingenious arguments 

 will be found in Chapter XV on Phosphorescence of the Sea. 



ANTOINE LE GRAND 



Another Cartesian, who devoted considerable space to lumines- 

 cences, was Antoine Le Grand (fl. 1650-1680) , Le Pere Antoine of 

 Douay. In his book, Institutio Philosophiae (London, 1675) , his 

 discourse followed Descartes closely in explaining luminous fish and 

 phosphorescence of the sea. He then elaborated on other lumi- 

 nous effects, presenting a typical Cartesian explanation. Le Grand 

 wrote: ^^ 



Some kinds of Fire do shine, and yet are destitute of all heat. For they 

 who use the Sea, observe that at sometimes when the Waves are dasht 

 against Rocks, they appear as if flames of Fire rebounded from them. 

 And thus also Rays of Light proceed from Rotten-ioood, and Saltfish, but 

 without any sensible heat. 



The Reason is, because the Matter of the 1st Element, which is shut 

 up in the Pores of such Bodies as these, tho' they be of force enough to 

 push the Globuli of the 27id Element, and to move the Retina, as much 

 as is sufficient to produce the perception of Light; yet it is too weak, to 

 separate the Earthly parts from one another, and to excite that agitation 

 in them, which is strong enough to produce heat. Fire, therefore only 

 shines when the Pores of the Terrestrial Particles are so narrow, that 

 they can only admit the first Element, and shut out every thick Body. 

 Thus when the pointed Needles, as it were of Salt do enter the strait 

 Pores of Fishes, and drive thence the Globuli of the 2nd Element, so as 

 to be open only for the admission of the matter of the 1st Element, they 

 do by this means make the Fishes Scales to shine like Glotu-worms. His- 

 torians tell us of a certain Fly in Neio Spain, of the bigness of a Beetle, 

 called Cocujus, whose Eyes do enlighten the Night, like a Wax Candle, 

 so that it serves for a Lanthorn to those that walk by Night, and for a 

 Lamp to burn in ones Chamber; and by the Light whereof one may 

 read and lurite; and have the same effect when the Insect is dead, as 

 when yet alive. 



Some Bodies afford great Heat, but are destitute of all manner of 

 Light: As the Blood of Live Animals, Horsdiing tending to putrefaction, 

 Quicklime sprinkled with tvater, in which things there is a hidden Fire 

 that burns and scorcheth, without the appearance of any Flame. 



The Reason is, because in such Bodies as these, the parts that sur- 

 round the 1st Element and that are agitated by it, are too soft and 

 limber to transmit the Action of Light. For tho' some of them swim on 

 the top of the matter of the 1st Element; and comply with its motion; 



*^ Le Grand, A., An entire body of philosophy according to the principles of the 

 famous Renate des Cartes, etc. Trans, from Latin of the learned A. Le G. by Richard 

 Blome l:99fF., London, 1694. 



