CONTENTS. XV11 



PAGE 



Sensation really mental 70 



Sight 72 



A Painter's eye 73 



SECTION IV. 



PRECAUTIONS IN OBSERVING. 



We must not be misled by size and weight 75 



Motion is the test of action 76 



Motion of heated water its effects 77 



Small beginnings not to be despised 78 



Acorns and oaks 79 



James Watt's monument 82 



Salt and salt-making 83 



Succession of events 85 



Losing one's way 87 



The beaten track 88 



Engineer houses 91 



Effect of the centre of gravity 92 



How to walk on slopes 93 



All things are useful 94 



There is information in every place 97 



Weight and measure 99 



First law of gravitation 100 



Knowledge of extension 101 



Muscular feeling, its measure 102 



Second law of gravitation 103 



Specific gravity variations of gravity 104 



Gravitation of distance 107 



Importance of gravitation 108 



The first cause . 110 



a3 



