REPORTS OF EUROPEAN OBSERVATORIES. 585 



The erection of the large refractor has to be delayed until next spring-. 

 The optical parts of the heliograph were purchased. Of smaller instru- 

 ments were purchased : 



A telescope by Schroeder m .078 aperture and m .84 focal distance ; a 

 comet-seeker of O ra .07O aperture; a 12-inch universal instrument by 

 Repsold ; a 5-inch reflector by Pistor and Martins ; a ^ s clock by Tiede; 

 a small star-spectroscope and an astatic mirror-galvanometer by Siemens 

 and Halske. 



For time-determinations a small transit was borrowed of the Berlin- 

 Observatory. 



Dr. P. Kempf, of r>erlin, has been employed as assistant. 



The observations on sun-spots and protuberances were continued by 

 Professor Sporer, assisted by Dr. Kempf. Xo spots were visible in 173 

 days out of 215 days of observation. 



The mean heliographic latitude of the spots amounted to ± 7° in the 

 first four months, ±9° in the second, and in the last four mouths they 

 were visible only iu the northern hemisphere. Only a small number of 

 the days were favorable for protuberance observations. Professor Sporer 

 completed the arrangement of the sun-spot observations for 1871-1873, 

 and, assisted by Dr. Kempf, computed those measured in the years 

 1871-1878. 



Dr. Vogel and Dr. Midler continued the examination of the solar 

 spectrum. 



Spectroscopic observations of lixed stars and nebulae were made by 

 Dr. Vogel. With the instruments employed could be seen those nebuke 

 mentioned by Ilerschel as "pretty bright," and under favorable condi- 

 tions the observer could determine the character of the spectrum of the 

 nebuke termed "faint." Only 51 nebuke spectra were examined. 



The examination of the surfaces of planets was continued by Dr. 

 Lohse with the 7^-inch telescope ; oS drawings were made of Jupiter and 

 observations made on Saturn. 



Dr. Lohse took photographic views of the Sun, a large number of 

 which were made with a photographic telescope of 0".057 aperture and 

 l m .5 focal distance. He also experimented in the laboratory on the new 

 and, in astro-photography, important process of employing gelatine in 

 place of collodion. 



Dr. Midler made determinations of refraction in various kinds of glass 

 intended for use in astronomical instruments, lie also continued his 

 photometric researches. 



Observations were made on 03 days on Mercury, Venus, Mars, Jupiter, 

 Saturn, Uranus, Neptune, and Vesta, 11m 1 comparison of which was made 

 either direct or with Capella, and on fixed stars. 



The time-determinations were made by Dr. Kempf with the refractor 

 and by meridian observations with Ertel's transit. 



The transit of Mercury was observed and the meteorological observa- 

 tions continued iu the usual manner. 



