INTRODUCTION. 



1. Physics. Briefly defined, physics is the science of 

 Matter and Energy. It aims to measure and investigate 

 the movements of or within any body, whether living or 

 dead, endeavoring to show how the forces of nature operate 

 upon or within the body to produce the phenomena associ- 

 ated with it. 



If we were endeavoring to ascertain how much the sun 

 weighs, how much energy in the form of heat and light is 

 being sent out from it daily, or how this energy is pro- 

 duced, our study would be one of Solar Physics. If we 

 were measuring the diameter of the earth, or the volume 

 of water in the oceans ; if we were endeavoring to ascertain 

 how the forces have operated to uplift mountain ranges or 

 to cut out deep canons or broad valleys, then our problem 

 would be one of Terrestrial or Earth Physics. If we were 

 measuring the strength of a horse; how many. pounds of 

 feed he must use to plow 10 acres of ground ; or endeavor- 

 ing to show how the oxygen he breathes and the food he eats 

 give rise to the energy of his muscles, our problem would 

 be one of Animal Physics. If we were studying how the 

 root forces its way through the soil ; how water is forced 

 into and through the roots to the leaves on the tree or how 

 the sunshine breaks down the carbon dioxide in the green 

 chlorophyll, our problem would become one of Plant Phys- 

 ics. If we are endeavoring to determine the dimensions 

 of beams to use in a barn ; how heavy a rod to use in a truss 

 or how to brace a building so that it may safely withstand 

 the pressure of the wind, then we are dealing with the 

 Physics of Architecture. And so we might go on emimcr- 



