Page:History of the Royal Astronomical Society (1923).djvu/69

 1830-40] ROYAL ASTRONOMICAL SOCIETY 53 invitations were issued to prominent men to be present at the inauguration of the great telescope on November 26, by the Duke of Wellington. But the invitations were countermanded, as the shutters of the dome were unsatisfactory ; and though the tele- scope was erected in 1832 January, we do not hear of any ceremony having taken place. This was no doubt because South at once declared his strong dissatisfaction with everything. In a letter to Schumacher (dated June 22) he pronounced the dome to be " a national disgrace " and the polar axis " a decided failure." In the following July, South went to Dorpat to see for himself if Struve's equatoreal really was as steady as alleged, returning in the beginning of November. An acrimonious correspondence between South and Troughton & Simms, which had commenced in the previous spring, was now resumed with great vigour and, thanks to South's ill-temper, went from bad to worse. Every obstacle was put in the way of the experiments and attempts to strengthen the mounting, by which its makers endeavoured to rectify the faults found with it, a task which turned out to be hopeless owing to the utter impossibility of getting South to listen to reason. The mounting was of the so-called English form. Judging by two sketches of it long afterwards published by Sheepshanks,* the upper and lower pivots were joined by what looks like two pair of semi-elliptical hoops. Each pair were in the middle connected by a St. Andrew's cross, in the centre of which were the supports of the pivots of the telescope, which was suspended like a huge transit instrument. The fault found with it was this : when the instrument was turned a little on its axis and then let go, a series of about a dozen short, quick vibrations followed, each lasting about 0-3 or 0-4 second. This was remedied by Sheepshanks by altering the bearing of the lower pivot. But now, when the instru- ment was turned in R.A. by laying hold of the telescope (it was quite steady when moved by the hour-circle) a vibration not unlike the former was discovered. This was obviously due to a twist in the great polar frame, in the construction of which no provision whatever had been made against twist. Sheepshanks therefore joined the two stays on each side of the telescope by pieces of wood parallel to the hour-circle ; bound these together with diagonal bracing, and finally covered the outside with a thin sheeting of boards parallel to the polar axis. " The instrument now looked as if it was made up of two decked boats, and in my opinion was handsomer than it was originally." Experiments with weights applied at the sides of the upper and lower ends of the polar axis showed that the twisting had quite disappeared.
 * In the pamphlet issued in 1854.