Page:History of the Royal Astronomical Society (1923).djvu/91

 1830-40] ROYAL ASTRONOMICAL SOCIETY 73 That Reichenbach's transit circle, mounted at the Gottingen Observatory about 1819, was not adopted, is not strange, since the construction was rather weak ; but these faults were remedied in Repsold's form of the instrument. But however mistaken this policy may have been, there was now everywhere a strong desire to make the utmost of every instrument, and to study and allow for its imperfections. There are several striking examples of this in papers published by the Society ; see, for instance, Sheepshanks' paper on the Cape Mural Circle. From the miscroscope readings at every tenth degree made by Fallows, the first astronomer there, Sheepshanks found that the circle had received some injury, but that the mean of the six miscroscopes was quite to be relied on.* This was afterwards confirmed by Henderson from readings of every 5. | A very thorough investigation of the Armagh mural circle by Robinson also appeared in volume 9 of the Memoirs. About this time transit instruments were often put to a use which, for some years, threatened to absorb a disproportionate amount of time. This was observing moon-culminating stars to determine the longitude of the observatory, or of some station where corresponding observations were made. Considering the exceedingly rough results obtained, it is strange that this method could remain in favour for some years, even for want of another. But it was not realised that there was no security even in a great number of observations. Thus, Robinson found for the longitude of Armagh, after allowing for irradiation, 26 m 3O s -4, which he thought could not be more than o s -i wrong. J In reality it was 5 s too small. The determination of difference of longitude by the transport of chronometers, which was first tried between Greenwich and Cambridge in 1828, gradually ousted the moon-culminating stars from fixed observatories. During most of the time he spent at Greenwich, Pond only observed a small number of standard stars (40 to 60) and published several small catalogues of them. In the Greenwich Observations for 1829 ne published a catalogue of 720 stars for the epoch of 1830, the largest catalogue based on observations made in England after Bradley's time. Of Johnson's catalogue of 606 southern stars, observed at St. Helena, we have already spoken. The next catalogue to be published in England was one of the Right Ascen- sions (only) of 1318 stars, observed at Lord Wrottesley's Observa- tory at Blackheath. Mention must also be made of another small star catalogue by an amateur, which, though published in abstract. t Memoirs, 8, 141-168. J Ibid., 4, 293 seq. Ibid., 10, 157-234.
 * Memoirs, 5, 325-339, and M.N., 2, 91-100. The latter is not a mere