234 ADVANCEMENT OF LEARNING 



surrounded with a thin pellicle of water, it stands still for 

 a time. 



16. Let the bounds of levity be inquired after; for 

 though men make the centre of the earth the centre of 

 gravity, they will perhaps hardly make the ultimate con 

 vexity of the heavens the boundary of levity; but rather, 

 perhaps, as heavy bodies seem to be carried so far, that 

 they rest, and grow as it were immovable; light bodies are 

 carried so far, that they begin a rotation or circular motion. 



17. Inquire the cause why vapors and effluvia are carried 

 so high as that called the middle region of the air, since the 

 matter of them is somewhat gross, and the rays of the sun 

 cease alternately by night. 



18. Inquire into the tendency of flame upward, which is 

 the more abstruse, because flame perishes every moment, 

 unless perhaps in the midst of larger flames; for flames 

 broken from their continuity are of small duration. 



19. Inquire into the motion and activity of heat upward; 

 as when heat in ignited iron sooner creeps upward than 

 downward. And thus much by way of example of our par 

 ticular topical inquiry. We must, for a conclusion, ad 

 monish mankind to alter their particular topics in such 

 manner, as after some considerable progress made in the 

 inquiry, to raise topic after topic, if they desire to ascend 

 to the pinnacle of the sciences. For my own part, I at 

 tribute so much to these particular topics, that I design 

 a particular work upon their use, in the more eminent and 

 obscure subjects of nature; for we are masters of questions, 

 though not of things. And here we close the subject of 

 invention. 



