Q^4f MECHANIC POWER, 



lated by Ihc external ftirauli, of which the occurrence feems 

 to agree with the animal neceffities : but the extenfive illuf* 

 trations which comparative anatomy affords on this point, are 

 much too copious for any detail in this place. 

 The nervous There are two ftates of mufcles, one a6live, which is that 



conftanUyaarveof Contraction, the other, a ftate of ordinary tone, or relaxa* 

 through life. tion, which may be coniidered pafiive, as far as it relates to 

 the mind ; but the fenforial or nervous power feems never to 

 be quiefcent, as it refpedts either the voluntary or involuntary 

 mufcles during life. The yielding of the fphinfters appears to 

 depend on their being overpowered by antagonift mufcles, 

 rather than on voluntary relaxation, as is commonly fuppofed. 

 I have now finiflied this endeavour to exhibit the more 

 recent hiftorical fads connefled with mufcular motion, 

 ponclufion* It will be obvious to every one, that much remains to be 



done, before any adequate theory can be propofed. I have 

 borrowed from the labours of others, without acknowledge- 

 ment, becaufe it would be tedious to trace every fa6l, and 

 every opinion to its proper authority : many of the views are 

 perhaps peculiar to myfelf, and I have adduced many general 

 aflumptions and conclufions, without offering the particular 

 evidence for their confirmation, from a defire to keep in view 

 the remembrance of retrofpeClive accounts, and to combine 

 them with intimations for future refearch. The due cultiva- 

 tion of this interefting purfuit cannot fail to elucidate many 

 of the phenomena in queftion, to remove premature and ill- 

 founded phyfiologlcal opinions, and eventually to aid in ren* 

 dering the medical art more beneficial, by eftabliftiing its 

 doflrines on more extenfive and accarate views of the animal 

 economy. 





VI. 



On the Meafure of Mechanic Power. In a Letter from 



Mr. J. C. HORNBLOWER. 



To Mr. NICHOLSON, 

 Dear Sir, 



Meafure of 1 AM glad to find that fomebody has feconded my motion 

 ^^^)t^& P^*?'^ concerning Iiorfe power, and I hope the fubje6l will not be dif- 



mifled 



