88 LIGHT SCIENCE FOR LEISURE HOURS. 



series of careful researches to determine the law accord- 

 ing to which Yenus may be expected to behave or to 

 misbehave herself; and the result is, that he has been 

 able to tell the observers exactly what they will have 

 to look for, and exactly what it is most important that 

 they should record. In 1769, observers recorded their 

 observations in such doubtful terms, owing to their 

 ignorance of the real significance of the peculiarities 

 they witnessed, that the mathematicians who had to 

 make use of those observations were misled. Hinc 

 illcB lacrymce. Hence it is that an undeserved reproach 

 has fallen upon the " exact science." 



The amount of the error resulting from the mis- 

 interpretation of the observations made in 1Y69 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 mill- 

 ion miles too great ; while even this enormous error 

 was as nothing -when compared with that which re- 

 sulted when the distances of the fixed stars were con- 

 sidered. 



But this is an altogether erroneous mode of esti- 

 mating 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 



