Human Physiology. 103 



to us from the sun, through the medium whose vibrations give 

 us all our sensations of comfort, and fill the earth and heavens 

 with beauty and glory. 



Of these vast forces of nature for ever active around us, man 

 as yet has made but little use. The heat of the sun every day 

 raises millions of tons of water into the air, which comes back 

 in rain, rivers, cataracts; it every day fixes vast quantities of 

 carbon in woody fibre, grass, grain, fruits, and vegetables; 

 gives movement to the air and forms currents in the ocean. 

 Gravitation raises tides that flow along our coasts and up our 

 estuaries and rivers. We are day by day exhausting the forces 

 of light and heat laid up in coal, but the winds, the descent 

 of waters, and the flow of tides, will for ever furnish abundant 

 force which can be transformed into heat and electricity, drive 

 our machinery, and warm and light our dwellings and towns. 

 When the coal is gone, every mountain stream, every slow 

 running river, every tideway on the sea, and all the currents of 

 the viewless air, will give us power, comfort, and light. 



Whatever may be the constitution of matter, it is evident 

 that it is with force that we have to do. It is that we see and 

 feel. Force, exercised by an intelligence and a will equal to 

 the creation and control of the whole universe, from the in- 

 finitely little to the infinitely great, fixes every atom, and 

 defines every form. Let the force of repulsion in matter cease 

 for one instant, and there would be a sudden collapse of mat- 

 ter. On the other hand, if the force of cohesive attraction 

 were an instant suspended if this power, whatever it may 

 be, which grasps all matter and holds all forms were suddenly 

 to cease to act, the entire universe and all it contains would 

 explode burst asunder like gunpowder, or nitro-glycerine, 

 leaving infinity of space filled with unrelated atoms, empty air, 

 without form and void, infinite silence, darkness, and death. 



There are probably many kinds or modifications of force in 

 nature unrecognised by science, though often seen in pheno- 



