424 Mhcdinncous Jnfefligeiicc. 



of March, the total loss was Goz., or a (iClli part in twenty-six 

 days, during the whole of which time the crape had remained 

 perfectly dry. 



4. Nature of Hail. — M. Delcros has published the idea thai 

 hail generally, and especially when small, is composed of the 

 fragments of crystalline spheres of ice. During ten years' obser- 

 vation, he had observed that the particles of hail were spherical 

 pyramids, varying in size, but having the same form. The apex 

 had sometimes disappeared, but when present was apparently 

 part of a hard nucleus ; next to this came another and larger 

 portion, radiated from the apex as a centre, and this was cover- 

 ed on the side opposite to the apex by a drusy portion of ice. 

 From the constancy of these appearances, he concluded that, in 

 the production of hail, a nucleus, composed of concentric 

 spheres, was first formed, on which a second radiated formation 

 was superposed, and that these masses were then broken into 

 pieces by a kind of explosion. 



In a storm which happened at la Bacconierc, in the Depart- 

 ment of Mayennc, in France, on the 4th of July, 1819, M. Del- 

 cros had an opportunity of observing these spheres, the fragments 

 of which he supposes generally form hail. Tlie hail-stones 

 which fell at that time were very large, some of them being 15 

 inches in circumference, and they were globular. When broken 

 they consisted of a very small nucleus, round which a larger had 

 formed, and then this again was surrounded by a very compact 

 radiated ice, more transparent than the rest ; the surface exhi- 

 bited the appearance of pyramids ranged one by the side of 

 another. Biblioth. Univer. 13. p. 154. 



5. Recession of the Magnetic Needle. — Col. Beaufoy is in- 

 duced to believe, from his Magnetical Observations, which are 

 published in Thomson's Annals, that the greatest variation 

 of the compass has been attained, and that the needle is now 

 slowly retrograding, and returning towards the North Pole. 

 During the last nine months of 1818, the variation gradually in- 

 creased, and was in the morning 24° 37' 4", and at noon 24*^ 41'. 



