fiOOK a] A^^ORISMS. 461 



the top of this tliermometer, and then notidfe if the water be 

 depressed by the heat.' 



Let the burning glass be tried on warm objects which emit no 

 luminous rays, as heated but not ignited iron or stone, or hot 

 water, or the like ; and observe wliether the heat become in- 

 creased and condensed, as happens with the solar rays. 



Let it be tried on common llame. 



The effect oi comets (if we can reckon them amongst meteors') 

 in augmenting the heat of the season is not found to be constant 

 or clear, although droughts have generally been observed to 

 follow them. However, luminous lines, and pillars, and openings. 

 and the like, appear more often in winter than in summer, and 

 especially with the most intense cold but joined with drought. 

 Lightning, and coruscations, and thunder, however, rarely hap- 

 pen in winter, and generally at the time of the greatest heats. 

 The appearances we term falling stars are generally supposed to 

 consist of some shining and inflamed viscous substance, rather than 

 of violently hot matter; but lot this be further investigated. 



Some coruscations emit light without burning, but are never 

 accompanied by thunder. 



Eructations and eruptions of flame are to be found in cold 

 climates as well as in hot, as in Icchind and Greenland; just as 

 the trees of cold countries are sometimes inflammable and more 

 pitcliy and resinous than in warm, as tlic fir, pine, and the like. 

 iiut the position and nature of the soil, where such eruptions are 



' In this thermometer, mercury was not dilated by heat or contracted 

 by cold, as the one now in use, but a mass of air employed instead, which 

 filled the cavity of the bulb. This being placed in an inverted position to 

 ours, that is to say, with the bulb uppermost, pressed down the liquor 

 when the air became dilated by heat, as ours press it upward ; and when 

 the lieat diminished, the liquor rose to occupy the place vacated by the 

 air. as the one now in use descends. It consequently was liable to be 

 affecled by a change in the temntrature, as by the weight oi air, and 

 could afford only a rude standard of accuracy in scientific investigations. 

 This theniiometer was not Bacon's own coitrivance, as is counnonly 

 supposed, but that of Drebbel. Ed. 



* Lalande is indignant that the Chaldeans should have more coirect 

 notions of the nature of comets than the niodein physicists, and charges 

 Bacon with entertaining the idea that they were the mere eflfects of 

 vapour and heat. This passage, with two others more positive, in the 

 **De Aug." (cap. xl.) and the " Descript. Globi Intellect." (cap. vi.) 

 certainly afford ground for the assertion ; but ii Bacon erred, he erred 

 with Galileo, and with the foremost spirits of the times. It is true 

 that Pythagor/*3 and Seneca had asserted their beliei in the solidity of 

 these bodies, but the wide dominion which Aristotle subsequently 

 exercised, threw their opinions iuLc the shade, a'ld made the opj>osit« 

 doctrine everywhere paramount. Ed. 



