374 Astronomy and Photography at Rome. 



ing been augmented by a famous refracting telescope of Cau- 

 choiXj by an astronomical theodolite of Gambey, by an excellent 

 chronometer of Breguet, and a capital meridian circle of Ertel. 

 Whether it be through the superior excellence of this particular 

 telescope, or the greater clearness of the Roman sky, the services 

 obtained from it have been most efficient, and such as may give 

 a new starting point for the science of astronomy. 



By the reports given in the memorial just published, the advan- 

 tages are fully shown which may be derived from observations 

 of the periodical failing stars, in corroboration of lunar and plan- 

 etary observations, for the accurate determination of the relative 

 position of places, not otherwise attainable by geodesical meas- 

 urement. The success of the operations used in the instances of 

 Rome, Naples, and Palermo, as respects each other, fully estab- 

 lishes the fact. The corrections obtained by these means have 

 been adopted by the French astronomers in the Connoissance des 

 Terns, although our Nautical Almanac is still in error. Taking 

 the difference in longitude of Greenwich and of Paris at 9 min- 

 utes 21.5 seconds, the correct position of the Observatory at Na- 

 ples will be Oft. 57m. ls.5, longitude east of Greenwich, and 

 40°51 / 46 // .6 north latitude; lessening by 7s.8, the longitude 

 hitherto given for Naples in the Nautical Almanac. 



The longitude of the Collegio Romano, at Rome, will then be 

 Oh. 49m. 55s.27 east of Greenwich, and its latitude 41° 53' 52 

 north, increasing by Os.57, the longitude hitherto given in the 

 Nautical Almanac. It is to be observed that there is a difference 

 of half a second of time in the longitude of Paris and Greenwich, 

 between the reckoning of the Connoissance des Terns and that 

 of the Nautical Almanac, which might as well be reconciled, see- 

 ing that they are both such great authorities, and Paris and Green- 

 wich such noted astronomical stations. 



// 



The mode of determining the longitude by observations of fall- 

 ing stars, was first suggested by Dr. Maskelyne, in the year 1783,* 

 and was made use of in 1802, in Germany, but it was reserved 

 for the Neapolitan astronomer Nobili to perfect the method, and 

 to point out the right way to be followed in the practice of those 

 observations. 



* See a notice on the determination of longitude by shooting stars, (this Journal, 

 Vol. xlii, p. 399,) where it will be seen that Dr. Halley and Mr. Lvnn have the 

 credit of suggesting this mode of observation as early as 1719 and 1727. 



