new Nebula and Clujlers of Stars • 46 5 
I corre&ed this defeat at the moment of obfervation by affixing 
to the tranfits of thefe excentric nebulae fuch proper marks of 
fins or minus in right afcenfion and polar diftance as I judged 
would bring them to a central obfervation. A fimilar method, 
well known to good aftronomers in eftimating their tenths of 
feconds by the proportional fpace over which the ftars move in 
their meridian paffage, makes it unneceffary to expatiate on the 
degree of accuracy that long practice enables us herein to^ 
obtain. 
If, however, I had been willing to delay giving this cata- 
logue till, by a repeated review of the heavens, the places had 
been more accurately determined, the work would undoubtedly 
have been more perfect; but whoever confiders that it requires 
years to go through fuch obfervations will perhaps think with 
me, that it is the beft way to give them in their prefect ftate, if it 
were but to announce the exiftence of fuch objects by way of 
inducing other aftronomers alfo to look out for them. Another 
motive for not delaying this communication is to (hew that my 
late endeavours to delineate the conftruflion of the heavens have 
been guided by a careful infpeQSon of them; and, probably, 
a catalogue which points out no lefs than one thoufand in- 
ftances of fuch lyftems as thofe are into which I have fhewn 
the heavens to be divided, will confiderably fupport what has 
been faidon this fubjedi: in my two laft Papers. 
When the diurnal motion of the earth was firft maintained, 
it could not but greatly add to the reception of this opinion 
when the telefcope expofed to our view Jupiter, Mars, and 
Venus, revolving on their axes-*;- and if thefe infttoc.es of 
* To thefe may now alfo be added Saturn, on whofe body I have, in the year 
1780, feen feveral 'belts, wdth fpots that changed their htuation in the courfe of a 
few nights. 
