222 Boyal Society, 



owing to the compound velocities, seem to tend from N.E. to 

 S.W. 



Although meteors differ very much from each other in some in- 

 stances, it is very difficult to classify them ; but an abundance of 

 them seems connected with a change of weather, and especially with 

 cirrostratus and cirrocumulus clouds. As to their direction, though 

 they sometimes converge towards one point, they rush at others 

 towards every point of the compass. He therefoi'e wavers only be- 

 tween an electric and a gaseous origin, — quoting electric experiments 

 referred to in England by the Abbe Bertholon, and gaseous ones by 

 Constable, as having produced excellent imitations. 



In the terrible night of the 7th of July 1834, a crowd of nimbi 

 collected around Vesuvius about 9 o'clock, shooting their lightnings 

 down towards the mountain accompanied by rain and hail. The 

 lightning was sometimes bluish and sometimes reddish. 



As to the periodicity of meteors. Dr. Forster finds that there are 

 decided changes in the electrometers also on the 10th of August and 

 13th of November ; and the greatest number he ever saw fell on the 

 10th of August 1811, just after a violent storm ; but when a storm 

 has happened some time before, the meteors are fewer at the two 

 periods observed. Also if one or more large meteors occur, there 

 are no small ones afterwards for a proportionate time, as if the atmo- 

 sphere had been cleared of the requisite material. Also it may be 

 remarked in general, that the winter and the higher latitudes are 

 least prolific of them. 



Fiery balls do not often occur, but are very powerful. Thus the 

 one seen in France and in England the 17th of July 1771, must 

 have been at an elevation of fifty-four miles, and the report of its 

 explosion was not heard till two minutes after its occurrence, like 

 the rolling of thunder ; but the observatory windows at Paris were 

 " ebranlees." It appeared larger and brighter than the]), and its 

 swiftness was estimated at twenty-four miles per second. 



From the quickly-increasing rarity of our atmosphere, Arbuthnot 

 thinks that at the height of sixty miles (the estimated height of tlie 

 meteor in 1718) the air is 30,000 times purer than on the level of 

 the sea. Yet Pringle estimated the height of the meteor of 1738 to 

 have been ninety miles. The diameter of some globes has been 

 estimated at 1^ mile. 



XXXVIII. Proceedings of Learned Societies. 



nOYAL SOCIETY. 

 [Continued from p. 770 

 June 17, " 13 ESEARCHES on the Function of the Intercostal 

 184<7. "-^ Muscles and on tlie Respiratory Movements, with 

 some remarks on Muscular Power, in Man." By John Hutchinson, 

 M.li.C.S. Communicated by Sir I3enjamin Brodie, Bart., F.R.S., &c. 

 The object of this paper is to demonstrate by models and dis- 

 sections the action of the intercostal muscles. 



