You are aware that I have been measuring the position and distance of the two stars [Greek: g]^1 and [Greek: g]^2 Virginis, which are both nearly of similar magnitudes, and also, that they have approximated to each other very rapidly. They were very close last year, and I expected to find they had crossed each other at this apparition, but to my surprise I find they have become a fair round disc, which my highest powers will not elongate--in fact, _a single star_! I shall watch with no little interest for the reappearance of the second [Greek: g]. My dear madam, Your truly obliged servant, W.H. SMYTH. * * * * * This eclipse was also seen by Sir John Herschel at the Cape of Good Hope, as well as by many astronomers in Europe provided with instruments of great optical power. In 1782 Sir William Herschel saw one of the stars of Zeta Herculis eclipse the other. In the "Connexion of the Physical Sciences" I have given an abridged account of Sir John Herschel's most remarkable discoveries in the southern hemisphere; but I may mention here that he determined the position and made accurate drawings of all the nebulae that were distinctly visible in his 20 ft. telescope. The work he published will be a standard for ascertaining the changes that may take place in these mysterious objects for ages to come. Sir William Herschel had determined the places of 2,500 nebulae in the northern hemisphere; they were examined by his son, and drawings made of some of the most remarkable, but when these nebulae were viewed through Lord Rosse's telescope, they presented a very different appearance, showing that the apparent form of the nebulae depends upon the space-penetrating power of the telescope, a circumstance of vital importance in observing the changes which time may produce on these wonderful objects. [Long afterwards Lord Rosse wrote in reply to some questions which my mother had addressed to him on this subject:--] FROM THE EARL OF ROSSE TO MRS. SOMERVILLE. CASTLE, PARSONSTOWN, _June 12th, 1844_. DEAR MRS. SOMERVILLE,