66 Origin, or Process of Causation of the Series. [CHAP. in. 



course, perfect accuracy, that is, the true observation, or the 

 voluntary steps and preliminaries on which this observation 

 depends. Whether voluntary or not, this result only can be 

 called intentional. But this result is not obtained. What 

 we actually get in its place is a series of deviations from it, 

 containing results more or less wide of the truth. Now by 

 what are these deviations caused? By just such agencies as 

 we have been considering in some of the earlier sections in 

 this chapter. Heat and its irregular warping influence, 

 draughts of air producing their corresponding effects, dust 

 and consequent friction in one part or another, the slight 

 distortion of the instrument by strains or the slow uneven 

 contraction which continues long after the metal was cast; 

 these and such as these are some of the causes which divert 

 us from the truth. Besides this group, there are others 

 which certainly do depend upon human agency, but which 

 are not, strictly speaking, voluntary. They are such as the 

 irregular action of the muscles, inability to make our various 

 organs and members execute precisely the purposes we have 

 in mind, perhaps different rates in the rapidity of the ner 

 vous currents, or in the response to stimuli, in the same or 

 different observers. The effect produced by some of these, 

 and the allowance that has in consequence to be made, are 

 becoming familiar even to the outside world under the name 

 of the personal equation in astronomical, psychophysical 

 and other observations. 



12. (2) The other example, alluded to above, is the stocl 

 one of cards and dice. Here, as in the last case, the resul? 

 is remotely voluntary, in the sense that deliberate volitio 

 presents itself at one stage. But subsequently to this stag* 

 the result is produced or affected by so many involuntar 

 agencies that it owes its characteristic properties to thes 

 The turning up, for example, of a particular face of a die : 



