50 MECHANICAL AND IMMECHANICAL PARTS 



ment, would be to dispose of the subject very hastily and 

 very irrationally. For the purpose of which we want, that of 

 evincing intention, we know a great deal. And what wo 

 know is this. We see the blood carried by a pipe, conduit, 

 or duct, to the gland. We see an organized apparatus, be 

 its construction or action what it will, which we call that 

 gland. We see the blood, or part of the blood, after it 

 has passed through and undergone the action of the gland, 

 coming from it by an emulgent vein or artery, i. e. by an- 

 other pipe or conduit. And we see also at the same time 

 a new and specific fluid issuing from the same gland by its 

 excretory duct, i. e by a third pipe or conduit ; which new 

 fluid is in some cases discharged out of the body, in more 

 cases retained within it, and there executing some impor- 

 tant and intelligible office. Now supposing, or admitting, 

 that we know nothing of the proper internal constitution 

 of a gland, or of the mode of its acting upon the blood; 

 then our situation is precisely like that of an unmechani- 

 cal looker-on, who stands by a stocking-loom a corn-mill, 

 a cardingr-machine, or a threshing-machine at work, the 

 fabric and mechanism of which, as well as all that passes 

 within, is hidden from his sight by the outside case; or, if 

 seen, would be too complicated for his uninformed, unin- 

 structed understanding to comprehend. And what is that 

 situation? — This spectator, ignorant as he is, sees at one 

 end a material enter the machine, as unground grain the 

 mill, raw cotton the carding-machine, sheaves of unthresh- 

 ed corn the threshing-machine : and when he casts his eye 

 to the other end of the apparatus, he sees the material is- 

 suing from it in a new state; and, what is more, m a state 

 manifestly adapted to future uses ; the grain in meal fit for 

 the making of bread, the wool in rovings ready for spinning 

 into threads, the sheaf in corn dressed for the mill. Is it 

 necessary that this man, in order to be convinced that de- 

 sign, that intention, that contrivance has been employed 

 about the machine, should be allowed to pull it in pieces ; 

 should be enabled to examine the parts separately ; explore 

 their action upon one another, or their operation, whether 

 simultaneous or successive, upon the material which is pre- 

 sented to them ? He may long to do this to gratify his 

 curiosity ; he may desire to do it to improve his theoretic 

 knowledge ; or he may have a more substantial reason for 

 requesting it, if he happen, instead of a common visitor, to 

 be a mill-wright by profession, or a person sometimes call- 

 ed in to repair such-like machines when out of order ; but^, 



