6 Br. Huggins [Jan. 20, 



itself, which is well marked in the diagram on the screen. The 

 meteors all shoot forth from one spot, which is called the radiant 

 point. A little consideration will show that this appearance is 

 really due to perspective, and represents the vanishing point of the 

 parallel courses in which the meteors are moving. Hence we learn 

 that they all belong to an enormous swarm of these bodies which the 

 earth is meeting, and further, we may find the direction in which 

 the swarm is moving relatively to the earth. Now the researches 

 of Olbers, H. A. Newton, and Adams showed that the November 

 shower is really a planetary swarm, revolving round the sun in 

 about 33j years. Further investigations of Schiaparelli, Leverrier, 

 and Oppolzer brought out the astonishing result that the path of 

 the November meteors is really identical with that of a comet 

 discovered by Tempel in 1865. Schiaparelli showed further, that 

 another independent group of meteors which appears in August, has 

 an orbit identical with the third comet of 1862. We are thus led 

 to see the close physical connection, and oneness of origin, if not 

 indeed identity of nature, of comets and of these meteors. Now the 

 meteors on these occasions are too minute to j)ass through the ordeal 

 of ignition by our atmosphere, they are burnt up before they reach the 

 earth, but at other times small celestial masses come down to us, which, 

 there can be little doubt, are of the same order of bodies, and similar 

 in chemical nature. The meteorites we have in our hands, contain 

 matter of the same kind probably as that which gives rise to cometary 

 phenomena. These two small meteorites, which fell at Estherville, 

 were kindly sent to me by Professor Newton, as probably good 

 examples of the sort of stuff of which the nuclei of comets are composed. 

 The question arises, are the revelations of the spectroscope about 

 comets in harmony with what w^e know of the chemical nature of 

 these celestial waifs and strays ? 



Meteorites may be arranged in a long series, passing from metallic 

 iron alloyed with nickel at one extremity, to those of a stony nature, 

 chiefly silicates, at the other. In meteorites more than twenty of 

 the elementary bodies have been found, including hydrogen, carbon, 

 and nitrogen, which the spectroscope has shown to be in comets. It 

 may be, however, that in the sun's action on comets, we have to do 

 not with the decomposition of the cometary matter, but with the 

 setting free of gases occluded within the meteoric matter, forming the 

 comet's nucleus. If the meteoric matter were decomposed, we should 

 expect a more complicated spectrum. 



In the year 1867 Professor Odling, lecturing on Professor 

 Graham's researches, lighted up this room with the gas brought by a 

 meteorite from celestial space. This meteorite, of the iron type, 

 yielded nearly three times its volume of gas, of which 85 per cent. 

 was hydrogen, 5 per cent, was carbonic oxide, and 10 per cent, 

 nitrogen. Since that time Professor A. W. Wright has experimented 

 with a meteorite of the stony type, containing, however, numerous 

 very small grains of metallic iron and sulphide of iron scattered 



