on the local arrangement of the celestial bodies in space . 323 
proceed to show what appears to be its construction by ap- 
plying to it the extent of telescopic vision ; but as I had pre- 
pared a gradually increasing series of reductions of the space- 
penetrating powers of my instruments for the purpose of 
measuring the Profundity of sidereal objects not visible to the 
eye, which I have called gaging powers, it will be necessary 
to give the following account of it. 
From the formula which has been given, I calculated a set 
of apertures, which by limiting the light of the finder of my 
seven feet reflector would reduce its space-penetrating power 
to the low gaging powers 2, 3, and I then limited in the 
same manner the space-penetrating power of my night glass, 
by using calculated apertures such as would give the gaging 
powers 3, 6 , 7 and 8. From the space-penetrating power of 
the 7 feet reflector, I obtained by limitation the successive 
gaging powers 9, 10 and upwards to 17. And lastly, by 
limiting the space-penetrating power of my 10 feet reflector, 
I carried the gaging powers from 17 to 28. 
For the purpose of trying these powers, I selected the 
bright spot in the sword handle of Perseus, as being proba- 
bly a protuberant part of the milky way, in which it is situ- 
ated. Its altitude at the time of observation was about 30 
degrees, and no star in it was visible. 
In the finder with the gaging power 2, I saw many stars ; 
and admitting the eye to reach to stars at the distance of the 
12th order, we may conclude that the small stars which were 
visible with this low power, are such as contribute to the 
brightness of the spot, and that their situation is probably 
from between the 12th to the 24th order of distances; at 
least we are certain, that if stars of the size and lustre of 
