on the Planet Venus. 
125 
EQUAL CARE TO THE SAME CIRCUMSTANCES AT THE SAME 
time, and not have seen them the same as 1 have given them. 
In my memoir, to which I here refer, those observations only 
which belong to the point in view are compared together ; 
but in other observations , almost innumerable , which I made partly 
before I had paid any particular regard to the inequality of the 
horns , and partly in the intervals , I did not perceive, any more 
than the author, either spots or any thing appertaining to the 
matter in question ; and consequently our corresponding observa- 
tions perfectly agree together. It is, however, and will remain 
a truth, that there is no such thing as a monopoly of disco- 
veries ; one man may luckily observe something to which the 
other did not direct his attention in the same manner, although he 
viewed it at the very same moment. Thus, for instance, since 
Hevelius's time many observers, provided with sufficiently 
powerful telescopes, have examined the moon, without per- 
ceiving the immense southern cordilleras of her edge, the 
perpendicular height of which, by indisputable observations, 
amounts to something more than a geographical mile, and 
which I have pointed out and delineated in my Selenotopo- 
graphical Fragments, under the names of Leibnitz and Doer- 
fel. And yet these high mountains are really there, and af- 
forded a magnificent spectacle at the commencement of the 
solar eclipse on the 5th of September last year, though they 
were not then exhibited in their greatest projection. So like- 
wise it is true, that several of the many important discoveries, 
on which the author has founded his eternal fame, might have 
been made as well by. other observers, who were furnished 
with good achromatic telescopes, if they had directed their 
