joo Mr. hek schel^s Account 
66 revenir plufieurs fois fur cette etoile ou Comete ; car abfolu- 
“ ment il a fallu l’obferver plufieurs jours de fuite pour s’ap- 
percevoir qif elle avoit un mouvement. 1 ’ 
I need not fay that I merely point this out as a temporary 
advantage in the method I have taken ; for as foon as we can 
have regular, conftant, and long continued obfervations by 
fixed inftruments, the excellence of them is too well known to 
fay any thing upon that fubjeCt : for which reafon I failed not 
to give immediate notice of this moving ftar, and was happy to 
furrender it to the care of the Aftronomer Royal and others, as 
foon as I found they had begun their obfervations upon it. 
Defcription of a micrometer for taking the angle of pofition . 
FIG. I. Reprefents the micrometer inclofed in a turned cafe 
of wood, as it is put together, ready to be uled with the tele- 
fcope. A is a little box which holds the eye-glafs. B is the 
piece which covers the infide work, and the box A is ferewed 
into it. C is the body of the micrometer containing the brafs 
work, fhewing the index plate a projecting at one fide, where 
the cafe is cut away to receive it. D is a piece, having a ferew 
b at the bottom, by means of which the micrometer is fattened 
to the telefcope, To the piece C is given a circular motion, in 
the manner the horizontal motion is generally given to Gre- 
gorian refleCtors, by the lower part going through the piece D, 
where it is held by the ferew E, which keeps the two pieces 
C and D together, but leaves them at liberty to turn upon 
each other. 
Fig. IL Is a feCtion of the cafe containing the brafs work, 
where may be obferved the piece B hollowed out to receive the 
3 box 
