LOED OXMANTOWN OX THE GEEAT NEBULA IN OEION. 
71 
ject as well as he could on the slit by viewing with a lens its image in a diagonal re- 
flector placed in front of the slit, and having its edge almost touching the slit, but not 
actually covering it, and swinging the tube till the brightest part of the nebula just passed 
the edge of the reflector, while the other observer looked into the spectroscope. The 
telescope was used in the Herschelian form, as it was desirable to get as bright an image 
as possible, but not of importance to get the best possible definition. 
The following is a list of the objects which we have examined, some of which have 
also been observed by Mr. Huggins. All these objects were examined both by Mr. 
Ball the present Assistant, and myself alternately. 
Gaseous Spectrum. 
Continuous Spectrum. 
Great nebula in Orion. 
2102 
2343 
4964 
Great neb 
2373 
2377 
2786'' 
2203 
2207 
2211 
2347 
2786. 
ula in Andromeda. 
No decided spectrum seen ; 
spectrum suspected to be 
continuous. 
Although the last six gave no decided spectrum, there can be very little doubt but that 
their spectra are continuous ; they were examined before our eyes had been accustomed 
to a faint or continuous spectrum by examining those of brighter objects, such as the 
nebula in Andromeda and the bright cluster in Canes Venatici. If they had given a 
gaseous spectrum we could hardly have failed to have seen it. 
Although in consequence of the smallness of the number of objects hitherto observed 
it would be premature to lay much stress on any inferences derived from these observa- 
tions, it may not perhaps be out of place to mention that in addition to the results arrived 
at by comparing our observations with those of Mr. Huggins (viz. that no cluster or 
resolved nebula yet observed gives a gaseous spectrum, and of the remainder those which 
give a continuous spectrum are generally of a more resolvable character than those which 
give a gaseous spectrum*) we find — 
1st. That no planetary or annular nebula yet observed has been found to give any but 
a gaseous spectrum, with in some cases a suspicion of a very faint continuous spectrum. 
2nd. That no nebula of the class generally denominated “rays” has yet been found 
to give a gaseous spectrum. 
3rd. That of the remaining objects observed, those which give a gaseous spectrum but 
are not denominated planetary are in one respect of the same character with them, viz. 
that they have in many places a well-defined termination to an almost uniformly bright 
* See Mr. Huggins’s paper, Philosophical Transactions, Part I. 1866. 
