S40 THE POPULAR SCIENCE MONTHLY. 



modern ideas. It contains numerous instruments which are maintained 

 in perfect order by the care of an instrument-maker attached to the 

 observatory. In the west meridian room are a transit-instrument by 

 Reichenbach (aperture 117 millimetres = 4.61 inches), and a meridian- 

 circle by the same artist (aperture 108 millimetres = 4.25 inches). 

 These are still in use, and by means of them M. Fergola has lately 

 determined the diiFerences of longitude of Naples with Rome and 

 Palermo. The east meridian room contains a meridian-circle by 

 Repsold, which has just been mounted, and wliich is one of the best 

 instruments of this class made by this celebrated artist. The tele- 

 scope has an aperture of 163 millimetres (6.42 inches), and a focal dis- 

 tance of two metres (8.74 inches). It has a single graduated circle, 

 one metre (39.37 inches) in diameter, and four microscopes. 



It is with this instrument that M. Fergola is observing the zone 

 of stars which the observatory of Naples has undertaken for the Ger- 

 man Astronomical Society. Besides the three meridian-instruments 

 the observatory of Naples has in active use two equatorials, and is 

 soon to obtain a third of larger dimensions. The first of these instru- 

 ments was constructed in 1811 by Reichenbach andUtschneider, and has 

 83 millimetres (3.27 inches) aperture. It is with this small instrument 

 that M. de Gasparis discovered nine asteroids, Ilygea^ Parthenope, 

 Egeria^ Eunornia, Psyche, 3Iassalia, Themis, Ansonia, and Beatrix. 

 The second equatorial was made by Merz, of Munich, and has 134 mil- 

 limetres (5.28 inches) aperture, and 2.06 metres (81.10 inches) focal 

 length. The objective is of so perfect a figure that, in spite of its 

 small dimensions, M. Nobile has been able to employ it in the meas- 

 urement of double stars of Struve's catalogue. (These were discov- 

 ered by Struve with an objective of 9.62 inches aperture.) 



Observatory of the Roman College : Director, Padre Sec- 

 chi; Astronomer, Padre Ferrari. The observatory under the direc- 

 tion of Padre Secchi is built upon the top of the cupola of the 

 church of St. Ignatius, near the Corso ; but in so solid a way that the 

 stability of the instruments, during the night at least, is quite satis- 

 factory. The prmcipal nistrument of the observatory is an equatorial 

 of 7.5 inches aperture, which is one of the chefs-d''oeuvre of Merz. 

 There is still another equatorial, by Cauchoix, of five inches aperture, 

 which is used for the daily observations of solar spots, and also a transit- 

 instrument by Ertel (aperture 92 millimetres = 3.62 inches), for time- 

 determinations. The situation of the observatory, in the centre of the 

 city, has forced its illustrious director to devote his efforts to the study 

 of physical astronomy, which in his opinion is too mvich neglected in 

 government observatories. 



To enumerate the magnificent works executed in this branch of as- 

 tronomy by Padre Secchi would require too much space, but I may 

 mention a new experimental method used by Padre Secchi in his 

 studies of the solar protuberances. For more than a year he has 



