464 Dr. Herschel’s Catalogue of One \ Thoufand 
To thofe who are accuftomed to the accuracy of tranfit 
inftru meats in regular obfervatories, this telefcope, notwith- 
standing the above-mentioned improvements, may perhaps 
appear far from being brought to perfection ; but they fhould 
recoiled thefize of the inftrument as well as its extenfive ufe, 
fince I can not only follow any objed for near a quarter of an 
hour, without difturbing the fituation of the apparatus, but 
can at pleafure, in a few minutes, turn it to any part of the 
heavens, and view a eeleftial objeCt wherefoever it may chance 
to be fituated, eyen the zenith not excepted. 
From this account it will be underftood, that the places of 
a few of the nebulae and clufters of ftars, determined before 
the 13th of December, 1783, may be faulty in right afcenfion 
as far as T of time, and in polar diftance to 8 or 1 o' of fpace. 
Afterwards the errors will be found to become gradually lefs 
confiderabie till the latter end of the year 1784, when, I 
fuppofe, they will feldom exceed half that quantity. From 
that period to Sept. 24, 1785, they will diminifh, and pro- 
bably not often amount to fo much as 3 or 4' in polar diftance, 
and 10 or 12," in right afcenfion. And now I flatter myfelf 
that all places, determined fince the laft mentioned time, will 
generally be true to a very fmall quantity ; fuch as 4 or 6 r/ in 
right afcenfion, and i| or 2' in polar diftance, and often much 
nearer. 
Some of the nebulae in that part of the heavens which, in 
a former Paper, I have called the ftratum of Coma Berenices, 
are indeed *fo crowded that there was no poflibility of taking 
them all in the center of the field of view, and a fomewhat 
lefs degree of accuracy may therefore be expected ; but having 
ufed myfelf by very frequent eftimations of the parts of the 
field of view to judge of their value in time as well as in Ipace, 
I corrected 
