310 NOVUM ORGANUM. 



danger (as it appears) of their being suffocated by the rarity of the 

 atmosphere. 



To the Second. 



3. The reflection of the rays of the sun in regions near the polar 

 circles is found to be very slight, and barren of heat ; so that the 

 Dutch who wintered in Nova Zembla, and were expecting their ship 

 to be liberated and disentangled from the mass of ice (by which it 

 was beset) about the beginning of July, were disappointed of their 

 expectation, and compelled to take to their boat. Thus the direct 

 rays of the sun seem to have but little power, even upon level ground, 

 nor have they much even when reflected, unless they be multiplied 

 and combined ; as is the case when the sun inclines much to the per 

 pendicular, because then the incident rays make acuter angles, so 

 that the lines of the rays are nearer together; while, on the other 

 hand, when the sun shines very obliquely, the angles are very obtuse, 

 and consequently the lines of the rays more distant from one another. 

 But in the meantime it must be remarked that there may be many 

 operations of the sun s rays, and those even of the nature of heat, 

 which are not proportioned to our sense of touch ; so that while in 

 respect of us they do not produce warmth, still, in respect of some 

 other bodies, they have the effect of heat. 



To the Second. 



4. Let this experiment be made. Take a lens fashioned in a con 

 trary way to the usual burning lenses, and place it between the hand 

 and the sun s rays, observing whether it diminishes the heat of the 

 sun as the burning lens increases and intensifies it. For it is mani 

 fest, in the case of optical rays, that in proportion as the lens is made 

 of unequal thickness, in respect of its centre and sides, will objects 

 appear magnified or contracted. And so it must be seen whether the 

 same is the case with heat. 



7*o the Second. 



5. Let experiment be diligently made whether, by means of burning 

 lenses of the greatest power and the best make, the rays of the moon 

 can be taken np and collected so as to produce even the smallest 

 degree of warmth. But if that degree of warmth be too subtle and 

 weak to be perceived and felt by the touch, recourse must then be 

 had to those glasses which indicate the condition of the air with 

 respect to heat and cold ; so that the rays of the moon may fall 

 through a burning lens, and be thrown on the top of a glass of this 

 kind ; and then let it be noted if the water be depressed by the 

 warmth. 



To the Second. 



6. Let the burning glass be also tried on some warm body, which 

 gives forth neither rays nor light ; as iron and stone heated, but not 

 ignited, or hot water and the like ; and let it be noted whether the 

 heat be increased or intensified, as in the case of the sun s rays. 



