Royal Astronomical Society. 73 



The optical part is doubtless admirable, though, perhaps, more con- 

 trol over the adjustment of the object-glass would be desirable ; 

 but Mr. Airy was far from satisfied with the rest of the instrument. 

 It did not obey its slow motions in right ascension and declination 

 with promptitude or accuracy, and the clock movement was deficient 

 in power. In short, though in the delicate and experienced hands 

 of M. Otto Struve the telescope is made to yield the utmost of its 

 powers, Mr. Airy does not consider the instrument, as he saw it, a 

 good specimen of mechanism. 



The heliometer, by the same artists, met with much greater ad- 

 miration ; and, indeed, Mr. Airy seems to have been very much im- 

 pressed with the beauty and excellence of all the other instruments. 

 He goes so far as to say, that he considers the meridional observa- 

 tions at Poulkova to be greatly superior to those of any other obser- 

 vatory with which he is acquainted. The transit and vertical circle 

 of Ertel, the miridian circle and prime vertical telescope of Repsold, 

 are praised, with some critical remarks, but no serious drawback. 

 Some doubt is expressed whether the prime vertical telescope would, 

 in other hands than those of M. Struve himself, give quite such 

 marvellous results as he obtains from it : still, in Mr. Airy's judge- 

 ment, a prime vertical telescope is far superior to any zenith sector 

 yet contrived for the investigation of aberration, parallax, &c, or 

 small differences of latitude ; and he considers the Poulkova results 

 as leaving all competition far behind. 



Mr. Airy " had the pleasure of witnessing complete observations 

 made by M. Struve with the prime vertical telescope, and pays the 

 tribute of his admiration to the caution, the delicacy, the steadily 

 waiting till the proper time, the promptitude at the proper time, 

 which distinguish the director's mode of observing." 



The excellence of the levels attached to the instruments at Poul- 

 kova, and the successful precautions constantly practised there to 

 avoid error in their use, are particularly noticed. The construction 

 of the standard barometer is pronounced to be " admirable," and the 

 noble library* considered "to be probably the most complete in the 

 world in reference to its peculiar subjects." 



On the Transit Instrument at the Bombay Observatory. By 

 Captain Shortrede. 



Captain Shortrede gives a short account of the instrument, its 

 mounting, &c, before he became acquainted with it. Such mistakes 

 as he relates can scarcely occur a second time, and therefore they 

 may be passed over in silence. 



When Captain Shortrede visited the Bombay Observatoiy during 

 his trigonometrical operations, he learned that the instrument was 

 considered incurably defective. A full consideration, however, led 

 him to a different opinion ; and as he is himself a workman, and 



beautiful work published by M. Struve, Description de £ Observatoire Aslro- 

 nomique Central de Poulkova, St. Petersbourg, 1845, 4to, with a volume of 

 plates, which has been distributed most liberally among astronomers. 



* A Catalogue of this library has been recently published, Librornm in 

 Bibliotheca SpcciiUe Pulcovensis contentorum Catalogus Systematicus, Petro* 

 poli Typis Acad. Scient. 1845, 8vo. 



