Mr Sang on some prevailing misconception s, S^c, 71 



of the effects of friction. Were all friction avoided, it would 

 be a matter of absolute indifference by what means the required 

 changes of motion might be produced ; it would then be of 

 no moment whether we employed the reciprocating or the ro- 

 tatory steam-engine, — whether we used the crank or the sun- 

 and-planet wheel, — farther than the mere expense of workman- 

 ship is concerned. And we have no other criterion for esti- 

 mating the superiority of one contrivance over another than 

 the comparison of the amounts of friction in the two cases. 



These statements will be startling enough to persons half 

 acquainted with the nature of machinery. " What," they will 

 ask, " does the obliquity of the crank cause no loss of force ! 

 Is there no force wasted in producing the reciprocating mo- 

 tion of the beam in the steam-engine ! And were they mere 

 dreams that we entertained of immense improvements in ma- 

 chinery P'' And when I assert, what is well known to every 

 one acquainted with the subject, that there is no loss of force 

 from the oblique action of the crank, that there is no force 

 wasted on the reciprocating motion of the beam, and that the 

 removal of friction is the only source of improvement in ma- 

 chines for transferring power, — I oppose the prejudices of mul- 

 titudes who ought to be better acquainted with the principles 

 of mechanics. 



The principles which regulate the balance of pressures, and 

 the movements of bodies, though discovered by man, are not of 

 human invention ; they are laws impressed by the Omnipotent 

 upon the material world — laws to which matter yields an im- 

 plicit, a perfect obedience. \These laws are few in number, and 

 the simplest language in which they can be expressed involves 

 the very statements that I have made. To exhibit, then, the 

 truth of these statements would be to examine the reality of 

 the fundamental laws of mechanics. To this examination I 

 will not proceed, but will content myself with founding my in- 

 vestigations on the more common forms in which these laws are 

 recognised. They naturally divide themselves into two classes : 

 those which relate to the pressures of the acting parts during 

 any momentary state of the machine, and those which relate 

 to the properties of the machine considered as in motion. Those 

 of the first or statical class, though at first sight very nume- 



