KNOWLEDGE OF HEAT. 



of matter. Their idealisations have assumed another 

 form, but the researches of modern science have only 

 established their universality and truth. 



The great agents at work in nature the mighty 

 spirits bound to never-ending tasks, which they pursue 

 with unremitting toil, are of so refined a character, that 

 they will probably remain for ever unknown to us. The 

 arch-evocator, with the wand of induction, calls ; but 

 the only answer to his evocation is the manifestation of 

 power in startling effects. Science pursues her inquiries 

 with zeal and care : she tries and tortures nature to 

 compel her to reveal her secrets. Bounds are, how- 

 ever, set to the powers of mortal search : we may not yet 

 have reached the limits within which we are free to 

 exercise our mental strength ; but, those limits reached, 

 we shall find an infinite region beyond us, into which 

 even conjecture wanders -eyeless and aimless, as the blind 

 Cyclops groping in his melancholy cave.* 



All we know of heat is, that striking effects are pro- 

 duced which we measure by sensation, and by instru- 

 ments upon which we have observed that given results 

 will be produced under certain conditions : of anything 

 approaching to the cause of these we are totally igno- 

 rant. The wonder-working mover of some of the 

 grandest phenomena in nature giving health to the 

 organic world, and form to the inorganic mass pro- 

 ducing genial gales and dire tornadoes earthquake 

 stragglings and volcanic eruptions ministering to our 

 comforts in the homely firt, and to advancement in 

 civilisation in the mighty furnace, and the ingenious 

 engine which drains our mines, or traverses our country 

 with bird-like speed, will, in all probability, remain for 

 ever unknown to man. The immortal Newton, many 

 of whose guesses have a prophetic value, thus -expresses 

 himself : " Heat -consists in a minute vibratory Bootion 

 in the particles of bodies, and this motion is commuiai- 



* Burns, in one of hi; most natural find pathetic letters. 



