THE NATIONAL SCIENTIFIC INSTITUTIONS AT BERLIN. 135 



which are of essential interest iu the study of the sun's activity. A 

 phiii was prepared with regard to the establishment, organization, and 

 equipment of the observatory, which was accepted by the Royal Gov- 

 ernment and sanctioned by legislative action of 1873-'74. 



The cost of the building for astrophysical observations was 874,000 

 mark ($218,500). ' . 



The budget for the Observatory is 71,600 mark ($17,900), of which 

 42,000 ($10,500) are paid out for salaries and compensation. 



The astro-physical institute is not an establishment for teaching, but 

 is intended exclusively for the scientific investigation of this new branch 

 of astronomy. Since the short existence of the Observatory many scien- 

 tists have taken part in its works, most especially as they relate to 

 spectral analysis and photography. 



The Observatory possesses the following larger telescopes: 



One large refractor of 20.8 centimeters (llf inches) aperture and 5.4 

 meters focus. Objective by Schroder, mountings by A. Repsold, Ham- 

 burg. Placed in the central cupola. Refractor by Grubb of Dublin, 

 aperture 20 centimeters (7^ inches), focus 3.2 meters ; in place in the 

 west cupola. A refractor by Steinheil, 13.5 centimeters aperture and 

 2.2 focus; placed in the east cupola. Photo-heliograph and mount- 

 ings by Repsold, objective by Steinheil, aperture IG centimeters and 

 focus 4 meters; placed in the southern addition to the main building. 

 Comet-seeker by Reinfelder and Hertel. 



The observatory possesses a large number of spectral apparatus, 

 among them one large by Schroder, for observations of the sun, and 

 one spectroscope by the same. John Browning furnished two spectro- 

 scopes for observations of the stars and for solar protuberances, re- 

 spectively. Other spectroscopes emanate from the shops of Hilger, 

 London; Schmidt & Hrensch, Berlin; Repsold, Hamburg; Topper, 

 Potsdam. In connection with the prism ai)paratus some finely gradu- 

 ated grates of glass and metal for the representation of grate spectra 

 may be mentioned ; among these are some excellent ones by WanschaflF, 

 Berlin. 



In addition to the larger apparatus for photographic work the equip- 

 ment for laboratory work is excellent. For j)hotometric representa- 

 tions of spectral analysis a large Ziillner photometer by Wanschaff and 

 several smaller photometers are employed. 



The (Jeodetic Tmtitiiie. — The purpose of the Institute is the improve- 

 ment of geodesy by scientific investigations. At the time of its estab- 

 lishment it was also intrusted with the Prussian portion of the European 

 Geodetic Survey ; in fact that undertaking was the cause of the estab- 

 lishment of the institute. The European Geodetic Survey developed 

 itself out of the Middle European Survey. In 18G2, at the suggestion 

 of Lieutenant General Baeyer — the collaborator of Bessels in the East- 

 ern Prussian Geodetic Survey and chief of the trigonometrical division 



