Conjirucilan of the Heavens'. f 
after we (hall find reafon, from experience and obfcrvation, to 
believe that there are parts of our fyftem where the ftars are 
not fcattered in the manner here fuppofed, we ought then to 
make proper exceptions. 
But to return : if feme other high gage be feleded from the 
table, fuch as 472 or 344, the length of the vifual ray will be 
found 461 and 415. And although, in confluence of what 
has been faid, a certain degree of doubt may be left about the 
arrangement and fcattering of the ftars, yet when I recoiled, 
that in thofe parts of the milky way where thefe high gages 
were taken, the ftars were neither fo fmall, nor fo crowded, 
as they muff have been on a fuppofttion of a much far- 
ther continuance of them, when certainly a milky or ne- 
bulous appearance muft have come on, I need not fear to have 
over-rated the extent of my vifual ray. And indeed every 
thing that can be faid to Ihorten it will only con trad the limits 
of our nebula, as it has in moft places been of fufficient length 
to go far beyond the bounds of it. Thus, in the fides of the 
ftratum oppofte to our lituation in it, where the gages often 
run below 5, our nebula cannot extend to 100 times the dis- 
tance of Sirius ; and me fame telefcope, which could fhew 588 
ftars in a field of view of 1 5 minutes, muft certainly have pre- 
fented me alfo with the ftars in thefe fttuations as well as the 
former, had they been there. If we fhould anfwer this by ob- 
ferving that they might be at too great a diftance to be per- 
ceived,. it will be allowing that there muft at leaft be a vacancy 
amounting to the length of a vifual ray not fhort of 400 times 
the diftance of Sirius ; and this is amply fufficient to make our 
nebula a detached one. It is true, that it would not be con- 
fiftent confidently to affirm that we were on an ifland unlefs 
we had adually found ourfelves every where bounded by the 
, ocean 3 
