ASTRONOMY AND METEOROLOGY. 305 



small that it cannot ever be seen, except by the aid of a first-class telescope. 

 The one employed by Dr. Donati was the great refractor of Amici, and had 

 a clear aperture of eleven inches, with a focal length of seventeen feet. Dr. 

 D. says : 



" On the 21st of April, about lOh. 30m., I perceived that the centre of 

 Brorscn's comet was about to pass exactly over a star of the twelfth mag- 

 nitude, and therefore carefully observed the passage. Gradually, as the 

 comet approached the star, the latter became fainter and badly defined, that 

 is, its disk was no longer round, but hazy, as if the star was shining through 

 mist. The diminution and diffusion of the stellar light increased as the 

 comet approached still nearer, so that when the centre of the latter covered 

 the star, it entirely disappeared for about thirty seconds. At the emersion, the 

 star presented the same appearance as at the immersion, and it shone, when 

 the nebulosity had entirely passed from over it, again perfectly round and 

 well defined." 



THEORY OF THE ASTEROIDS. 



In a paper published in the Comptes Rendus, by M. Le Verrier, on the aste- 

 roids, that eminent astronomer shows by calculation that the sum of the 

 mass of fragmentary planets, called asteroids, cannot exceed one-fourth of 

 the earth's mass ; and also shows it probable that their mean mass or sys- 

 tem is at its perihelion, and consequently nearest the earth, at the time when 

 the earth itself is on the side of the summer solstice. This, it is urged, is 

 confirmatory of the theory that aerolites are the minute outriders of the 

 asteroids. 



CHANGES IN THE INTENSITY OF THE HEAT OF THE SUN. 



In a memoir recently published in the contributions of the Smithsonian 

 Institute, by L. W. Meech, " On the relative intensity of the Heat and Light 

 of the Sun upon the different Latitudes of the Earth," the author deduces, 

 among other results, that taking into view the fact that the obliquity of the 

 ecliptic, 2000 years ago, in the time of Hipparchus, 128 B. C., was 23 43', 

 and is 23 27F, and that therefore the sun then rose higher in summer than 

 now, the summer heat of that period was two-tenths of a degree Fahrenheit 

 hotter than that of the present, while the winter was the same amount 

 colder. 



ON THE ORIGIN OF HAIL. 



In a discussion on the above subject at the last meeting of the British As- 

 sociation, Admiral Fitzroy said, that he had no doubt whatever that colder 

 currents of air coming from the polar regions, and breaking by or mingling 

 with the currents coming up from the equatorial regions, loaded with vapor, 

 played a very important part in the phenomena. As it had been a question, 

 whether hail was ever experienced in the inter-tropical parts of the earth, 

 he could decidedly answer in the affirmative, as he had experienced several 

 heavy hail-storms even within a few degrees on either side of the equator. 



INFLUENCE OF THE MOON ON THE WEATHER. 



At the Leeds meeting of the British Association, 18o8, Mr. Harrison pre- 

 sented a paper " On the Influence the Moon exerts on Temperature," and he 



