Revelations in the Sidereal Heavens. 115 



absorbed the keenest interests of science, — has been decidedly 

 great, and the new knowledge acquired, concerning the 

 handiwork of the Great Creator, amply satisfying of even 

 sanguine anticipations. 



Transferred to the ledger records from the journals of the 

 Observatory (comprising only a selection from the general 

 observations) about 700 catalogued nebulae, Dr S. found, Sep- 

 tember last, had been already examined, and new nebula?, or 

 nebulous knots, discovered merely incidentally, to the amount 

 of 140 or more. The number of observations, involving sepa- 

 rate sets of the instrument, recorded in the ledger (exclusive 

 of very many hundreds, possibly thousands, on the moon and 

 planets), amount to near 1700, involving several hundreds of 

 determinations of position and angular measurements with 

 the micrometer on the far distant stars. The carefully drawn 

 configurations, eliciting new characteristics, exceed 90, and 

 the rough or less-finished sketches amount to above 200. Of 

 the 700 catalogued nebulae already examined, it should be 

 observed, that in fully one-half, or more, something new has 

 been elicited. 



In speaking of the effects of the flood of light accumulated 

 by the six-feet speculum of the Earl of Rosse, Dr Scoresby 

 remarked, that this peculiarity of the instrument (connected 

 as it is with due length of focus and admirable definition) en- 

 abled it to reach distances in space far beyond the powers of 

 any other instrument. This was its peculiar province ; and 

 in this, as to existing instruments, there was not, nor, as he 

 hoped to shew, could there be, any competition. For com- 

 paring the space-penetrating power of the six-feet speculum 

 with one of two feet (which has rarely been exceeded) we 

 find it three to one in favour of the largest, with an accumu- 

 tion of light in the ratio of 6 2 to 2 2 , or 9 to 1. On comparing 

 the powers of this magnificent instrument with those of a 

 refractor of two feet aperture, the largest hitherto attempted, 

 we have a superiority — making a due allowance for the loss 

 of light by reflection from two mirrors, and assuming an 

 equal degree of perfectness, figure, and other optical re- 

 quirements in the refractor, and no allowance for absorp- 

 tion of light— in the ratio of about 4-5 to 1, as to light, 



H 2 



