40 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Klein, in 1871. The latter states that, among the various 

 and sometimes fanciful theories that have been devised to 

 explain this phenomenon, Safarik omits to enumerate that 

 which seems to him most likely to be the true one: namely, 

 the possibility that the illumination of the dark half of Venus 

 is effected by means of the light reflected from a satellite to 

 that planet. This theory has been especially developed by 

 Klein in his work on descriptive astronomy, in which he also 

 explains why the secondary illumination of Venus is so sel- 

 dom visible in the great telescopes, and why the question 

 whether Venus possess a moon must still remain an open one. 

 7 G lr ,1874,154. 



THE SOLAR ECLIPSE OF 1874. 



The observations of the total eclipse of the 16th of April, 

 1874, have been successfully carried out by Mr. Stone, director 

 of the observatory at the Cape of Good Hope. He noticed 

 that the coronal atmosphere was apparently, as might have 

 been expected at this period of minimum sun-spots, smaller 

 than in 1871, while the clearness of the air at his station re- 

 duced the phenomena peculiar to the earth's atmosphere to 

 a minimum. The spectrum of the reversing layer was again 

 seen, thus confirming Young's observation of 1870. Perhaps 

 the most important observation made by Mr. Stone is that 

 referring to the visibility of the Fraunhofer lines in the spec- 

 trum of the coronal atmosphere, showing thereby that the 

 latter reflects the light of the photosphere. 7 C, 1874, 60. 



ANCIENT SUN-DIALS. 



A visit to Pompeii, as also a visit to the Museum of Pom- 

 peian Antiquities at Naples, brings to notice a great number 

 of sun-dials, which are sometimes ornamented very beauti- 

 fully. As the division of the day into hours was in Roman 

 times very different from that at present in use, since they 

 divided the day, from sunrise to sunset, into twelve equal 

 parts, the hours being therefore of varying length, it follows 

 that their sun-dials must have had a very different construction 

 from our own. The face of their ancient dials is a concave 

 spherical surface, worked in a stone, and set to face the south. 

 A metal pencil is fastened on the upper side of the block of 

 marble, so that its point is precisely in the centre of the 



