CONTENTS TO VOL. 11. 



CHAPTER XXI. 



THE ELEMENTS. 



Consolidation of uses, page 2; i. air, 2 ; reflecting light, 3; evapo- 

 rating fluids, 3 ; restoratives of purity, 4 ; ii. vv^ater, 7 ; pu- 

 rity, 7 ; insipidity, 7 ; circulation, 8 ; iii. fire, 8 ; dissolvent 

 power, 9; iv. light, 9; velocity, 9; tenuity, 10. 



J^Tote 1, on the purification of the air by the respiration of plants, 

 page 5 ; 2, on the purification of the air by the agitation of 

 w^ater, 6; 3, on the adaptation of the conducting powers of 

 different substances to the wants of the animal and vegeta- 

 ble kingdom, 9; 4, on the composition of light, 11. 



CHAPTER XXII. 



ASTRONOMY. 



Fixing the source of light and heat in the centre, 17 ; permanent 

 axis of rotation, 21 ; spheroidicity of the earth, 24; of cen- 

 tiipetal forces, 26 ; attraction indifferent to laws, 27; admis- 

 sible laws within narrow limits, 30 ; of admissible laws, the 

 present the best, 32 ; united attraction of a sphere, the same 

 as of the constituent particles, 33; the apsides fixed, 34; 

 figures of the planetary orbits, 40 ; Buffon's hypothesis, 42. 



J^oU 5, on the telescopic appearance of the sun, 17; 6, on the te- 

 lescopic appearance of Saturn, Jupiter, Mars, and Venus, 

 20; 7, (by Bishop Brinkley,) on the changes of the earth's 

 surface, as proved by geological discoveries, 23 ; 8, ongravi- 



