282 HERSCHEL. 
manner we must endeavour to distinguish separately the 
two members of certain double stars very close to each 
other. He said if you wish to assure yourself that 7 
Coronz is a double star, first direct your telescope to a 
Geminorum, to § Aquarii, to “ Draconis, to p Hereculis, 
to a Piscium, to « Lyre. Look at those stars for a long 
time, so as to acquire the habit of observing such objects. 
Then pass on to § Urse majoris, where the closeness of 
the two members is still greater. In a third essay se- 
lect « Bootis (marked 44 by Flamsteed and 7 in Harris’s 
maps) *, the star that precedes a Orionis, n of the same 
constellation, and you will then be prepared for the more 
difficult observation of 7 Coron. Indeed 7 Corone is a 
sort of miniature of 7 Bootis, which may itself be consid- 
ered as a miniature of @ Gem. (Philosophical Trans- 
actions, 1782, p. 100.) 
As soon as Piazzi, Olbers, and Harding had discov- 
ered three of the numerous telescopic planets now known, 
Herschel proposed to himself to determine their real 
magnitudes ; but telescopes not having then been applied 
to the measurement of excessively small angles, it became 
requisite, in order to avoid any illusion, to try some ex- 
periments adapted to giving a scale of the powers of those 
instruments. Such was the labour of that indefatigable 
astronomer, of which I am going to give a compressed 
abridgment. 
* In the selection of i Bootis as a test, Arago has taken the precau- 
tion of giving its corresponding denomination in other catalogues, and 
Bailey appends the following note, No. 2062, to 44 Bootis. ‘In the 
British Catalogue this star is not denoted by any letter: but Bayer 
calls it 7, and on referring to the earliest MS. Catalogue in MSS. vol. 
xxy., I find it is there so designated; I have therefore restored the 
letter.” (See Bailey’s Edition of Flamsteed’s British Catalogue of 
Stars, 1885.) The distance between the two members of this double 
star is 3// -7 and position 28° 5. See “ Bedford Cycle.”— Translator. 
