VENUS ON THE SUN'S FACE. 77 



make use of those observations were misled. Hinc 

 illce lacrymce. Hence it is that an undeserved reproach 

 has fallen upon the ' exact science.' 



The amount of the error resulting from the misin- 

 terpretation of the observations made in 1769 was, 

 however, very small indeed, when its true character is 

 considered. It is, indeed, easy to make the error seem 

 enormous. The sun's distance came out some four 

 millions of miles too large, and that seems no trifling 

 error. Then, again, the resulting estimate of the dis- 

 tance of Neptune came out more than a hundred 

 million miles too great; while even this enormous 

 error was as nothing when compared with that which 

 resulted when the distances of the fixed stars were 

 considered. 



But this is an altogether erroneous mode of estimat- 

 ing the effect of the error. It would be as absurd to 

 count up the number of hairs' breadth by which the 

 geographer's estimates of the length and breadth of 

 England may be in error. In all such matters it is 

 relative and not absolute error we have to consider. 

 A microscopist would have made a bad mistake who 

 should over-estimate the length of a fly's proboscis by 

 a single hair's breadth ; but the astronomer had made 

 a wonderfully successful measurement of the sun's dis- 

 tance who deduced it within three or four millions of 

 miles of the true value. For it is readily calculable 

 that the error in the estimated relative bearing of the 

 feun as seen from opposite sides of the earth corresponds 



