18 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



eses, the conclusion was that, to observe the planet in transit, 

 astronomers must wait till 1881 or 1885, although there is a 

 possibility of a transit in 1877. It has been suggested that 

 the total solar eclipse of 1878 will be a favorable opportunity 

 to search for it ; and if an approximate position of it for that 

 time is given, the planet must be sure of detection, if it really 

 exist. 



Lassell, of England, examined Venus on the 12th and 13th 

 of July for the purpose of seeing the unilluminated portion 

 of the disk, but he was not successful. 



Ertborn, of Antwerp, publishes in the Bulletin of the Bel- 

 gian Academy a series of observations on spots on Venus. 



Trouvelot, of Cambridge, is still pursuing his observations 

 of the planets. During the present year he has made 112 

 sketches of Jupiter, 80 sketches of Mars, and several of Sat- 

 urn. The weather has been unfavorable for Mars, and a 

 quiet atmosphere has not yet been obtained. A spot which 

 appeared on Jupiter April 15 is still visible, and has been 

 observed by Trouvelot twenty times. The adopted period 

 of rotation does not agree with that indicated by the spot. 

 If the adopted period be correct, the spot has a retrograde 

 proper motion of great regularity, " almost too regular," as 

 M. Trouvelot remarks. 



Mr. Brett has published speculations on the " specular re- 

 flection" of Venus, the main idea of which is that Venus 

 reflects the sunlight from a vitreous envelope, much as a 

 thermometer-bulb would do. Mr. Brett suggests to observ- 

 er^ of the next transit of Venus the propriety of looking in 

 the globe of Venus for a reflected image of the earth, which 

 will appear as a " minute nebulous speck of light." This 

 " nebulous speck" would be less than one fiftieth of a second 

 of arc in diameter. Considering the difficulty of seeing Venus 

 herself when very close to the sun, the hope of carrying out 

 the provisions of this plan is rather a forlorn one, particular- 

 ly as the light of this "speck" is diminished by reflection, 

 and is to be seen close to a bright background. 



Cj CD 



On December 7, 1876, Professor Hall, of the Naval Observa- 

 tory at Washington, discovered on the disk of Saturn a brill- 

 iant oval white spot, which was observed to move across the 

 disk for about an hour. It was central at G h. 18 m. "Washing- 

 ton mean time. Information was sent to various observato- 



