Length and Space. 65 



no other sense whatever. It i;; measurable in three ways; 

 that is, has three dimensions, — leni,nh, breadth, and thick- 

 ness. Bodies can be measured in these three respects. 



1. — If one body is laid upon my finger, and I feel the 

 impression from the tip of the finger to the middle, and if 

 another is laid upon it, so that I feel the impression from 

 the one end of the finger to the other ; there is, then, a 

 manifest difference between the two impressions. I know 

 not in what this difference consists ; but, to make known 

 to my companions that 1 [)crceive a difference, I call the 

 object from which 1 receive the former impression short, 

 or SHORTER, and that from which I receive the latter 

 impression long, or longer. By applying the same objects 

 to different parts of the body, corresponding impressions 

 will be received. Thus, it will appear, that objects which 

 are s/wrt in one case, are so in every case ; and that those 

 which are lotig in one case, arc long always. A belief is 

 thus induced, that nature is uniform in her operations; 

 and we never doubt, that objects that seemed longer at one 

 time, will be found so at another. ]iy directing the eye to 

 the two objects, different impressions are received through 

 this sense; and after a multitude of trials, we learn to 

 distinguish long from short objects by their different 

 appearances. In some bodies, namely, sonorous ones, 

 long from short ones, may be distinguished by the car, in 

 consecjuence of the diUcrent sounds which they euiit when 

 tttruck. 'i'his information is generally very indefwiite, but 

 it admits of considerable improvenjcnt by practice and 

 study. 



'i'liUK, it appears that our ideas of length, imply merely 

 the perception of a difference between the impressions madt- 

 upon them by long and short objects. All wc know of the 



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