I have very reluctantly postponed so long replying to your inquiries respecting the telescope, but there were some points upon which I was anxious to be enabled to speak more precisely. The instrument we are now using is 3 feet aperture, and 27 feet focus, and in the greater proportion of the nebulae which have been observed with it some new details have been brought out. Perhaps the most interesting general result is that, as far as we have gone, increasing optical power has enlarged the list of clusters, by diminishing that of the nebulae properly so-called. Such has always been the case since the nebulae have been observed with telescopes, and although it would be unsafe to draw the inference, it is impossible not to feel some expectation that with sufficient optical power the nebulae would all be reduced into clusters. Perhaps the two of the most remarkable of the resolved nebulae are Fig. 26 and Fig. 55. In several of the planetary nebulae we have discovered a star or bright point in the centre, and a filamentous edge, which is just the appearance which a cluster with a highly condensed centre would present in a small instrument. For instance, Figs. 47 and 32. We have also found that many of the nebulae have not a symmetrical form, as they appear to have in inferior instruments; for instance, Fig. 81 is a cluster with long resolvable filaments from its southern extremity, and Fig. 85 is an oblong cluster with a bright centre. Fig. 45 is an annular nebula, like Herschel's drawing of the annular nebula in Lyra. I have sent drawings of a few of these objects to the Royal Society, they were forwarded a few days ago. We have upon the whole as yet observed but little with the telescope of 3 feet aperture. You recollect Herschel said that it was a good observing year, in which there were 100 hours fit for observing, and of the average of our hours I have not employed above 30. We have been for the last two years engaged in constructing a telescope of 6 feet aperture and 52 feet focus, and it would have been impossible to have bestowed the necessary attention upon it had we made a business of observing. That instrument is nearly finished, and I hope it will effect something for astronomy. The unequal refraction of the atmosphere will limit its powers, but how far remains to be ascertained.... Lady Rosse joins me in very kind remembrances and believe me to be, Dear Mrs. Somerville, Yours very truly and ever, ROSSE. * * * * * [Sir John Herschel wrote to my father from the Cape:--] FROM SIR JOHN HERSCHEL TO MR. SOMERVILLE. FELDHAUSEN, NEAR WYNBERG, C.G.H., _July 17th, 1830_. MY DEAR SOMERVILLE,