164 Star anfr TOeatber (Soggtp 



clouds. The best nights for observing were after heavy 

 rain. Mr. Burns having observed at a distance of only 

 seven miles from the heart of London, he thought it 

 obvious that the determinations must be affected by a 

 large error arising from the illumination of the atmo- 

 sphere by the street lamps and other terrestrial sources. 



CLOUDS AT SUNSET 



Why does a bank of cloud often arise in the west 

 at sunset after a clear day ? This is one of several 

 interesting questions put to me by Mr. Samuel Scott, 

 of Bramley, Yorkshire. It is a point I have not 

 previously thought of, but let us see what can be 

 made of it. In the first place, the very important 

 fact must be realised that most of our weather comes 

 from a westerly quarter. Let us suppose, then, that 

 the sun has just set. The withdrawal of his rays has 

 led to a rapid cooling of the air. A breeze comes up 

 from the westward, laden with warm air. This 

 mingles with the air cooled by the departure of the 

 sun and quickly condenses, thus forming a mass of 

 cloud which, as the breeze advances eastward, gradually 

 overspreads the whole sky. Should the clouds remain 

 hanging about the west horizon it seems to me indica- 

 tive of the fact that the breeze has died down before 

 reaching the spot where the observer has a clear sky 

 overhead. 



THE MULTITUDINOUS STARS 



It was estimated by the late Simon Newcomb that 

 the largest telescopes and the camera combined could 

 reveal fully a hundred million stars, but the late Lord 



