Me ; ae 
100 BAILLY. 
problematical correctness. Finally, to complete the ob- 
servation, he must read off the microscopical divisions 
of the graduated circle, and for what opticians call 2- 
dolent vision (the only sort that the ancients ever re- 
quired) must substitute strained viston, which in a few 
years brings on blindness.* 
When he has scarcely escaped from this physical and 
moral torture, and the astronomer wishes to know what 
degree of utility is deducible from his labours, he is ob- 
liged to plunge into numerical calculations of a repelling 
length and intricacy. Some observations that have been 
made in less than a minute, require a whole day’s work 
in order to be compared with the tables. 
Such was the view that Lacaille, without any soften- 
ing, exhibited to his young friend; such was the profes- 
sion into which the adolescent poet plunged with great 
ardour, and without having been at all prepared for the 
transition. 
A useful calculation constituted the first claim of our 
tyro to the attention of the learned world. 
The year 1759 had been marked by one of those great 
events, the memory of which is religiously preserved in 
scientific history. A comet, that of 1682, had returned 
at the epoch foretold by Clairaut, and very nearly in the 
region that mathematical analysis had indicated to him. 
This reappearance raised comets out of the category of 
sublunary meteors ; it gave them definitely closed curves 
* This long list of supposed difficulties in making an exact observa- 
tion is hardly worthy of a zealous astronomer. Our author shows no 
enthusiasm for his subject here, and ends by ascribing the whole 
feremiad to Lacaille, a man of very great practical perseverance. It 
is to be regretted that Arago never refers to observations of his own, 
but constantly quotes from others, nor does he always select the best. 
— Translator’s Note. 
