84 TOPICS OF INQUIRY 



may see among painters who use a phial filled with water 

 beside their candle. 



Whether all bodies of any considerable size do not reflect 

 light, must also be considered. For light, as may be be 

 lieved, either goes through or is reflected: from which 

 cause the moon, though it be an opaque body, may yet 

 reflect light by reason of its magnitude. 



We must ascertain too whether or not the aggregation of 

 lucid bodies multiplies light. And in regard to bodies 

 equally lucid there is no doubt of this : but it remains for 

 inquiry whether or not a light, which is evidently overcome 

 and rendered of itself invisible by a greater light, doth not 

 yet add some light. Whatsoever is bright also contributes 

 somewhat of light, for an apartment is much lighter when 

 hung with silk than with cloth. Light is also multiplied 

 by refraction ; for gems when cut into angles, and glass 

 when broken, shine much more than if they were smooth. 



vii. Modes of destroying Light. 



The modes of destroying light must also be remarked : 

 as by the exuperance of greater light, and by dense and 

 opaque mediums. The sun s rays certainly, falling on the 

 flame of a fire, make the flame seem like a kind of whiter 

 smoke. 



vni. Operations or Effects of Light. 



We have to consider the operations or effects of light, 

 which, it seems, are few, and possess little power of changing 

 bodies, especially solids. Light above all things generates 

 itself, other qualities sparingly. Light doth certainly in 

 some measure attenuate the air, is grateful to the spirits of 

 animals, and exhilerates them; it excites the slumbering 

 rays of all colours and visible things, for every colour is 

 the broken image of light. 



ix. Continuance of Light. 



The continuance of light must be investigated ; which, 

 as it appears, is momentary. For light doth not illuminate 

 an apartment more when it hath continued there for many 

 hours, than for any single moment; which is not so in 

 respect of heat, &c.; for the first portion of heat remains, 

 and a new one is added to it. Yet twilight is by some 

 thouo-ht to arise from the traces of the sun. 



