David Forbes — On Meteorites. 227 



especially during the great meteoric displays whicli occur in the 

 middle of the month of November, and will have noticed how one 

 of them, appearing in the distance as a mere luminous point like an 

 ordinary star, becoming, as it approaches nearer, larger and larger, until 

 it looks like a globe of fire surrounded by a brilliant vapour, and 

 having a tail like a comet. In the day-time, however, on account of 

 the sun's light, and the emission of smoke and vapour from the 

 meteor itself, it often assumes the appearance of a small cloud of 

 singular form and colour, and in both cases ultimately bursts with an 

 explosion. The apparent size of meteors is very deceptive, even 

 when measurements are attempted based on the angle made by their 

 apparent diameter and their calculated distance, the reason being 

 that the apparent diameter is not that of the solid meteorite itself, 

 but only of the photosphere or illuminated atmosphere which sur- 

 rounds it ; for this reason we often find them described as being even 

 as large as the full moon for example, although the bulk of the 

 meteorite when fallen is seen to bear no relation whatever to such a 

 size. It is rarely, however, that this test can be applied, as most 

 commonly the meteors, when they enter our atmosphere, or soon 

 after, burst with a terrific explosion, scattering their fragments, 

 often thousands in number, over a vast area, and frequently miles 

 apart. At this moment it occasionally happens that the fragments 

 themselves, whilst still in the air, assume the appearance of so many 

 distinct meteors in the act of falling to the ground. The noise of 

 the accompanying explosion has on different occasions been likened 

 to the roll of thunder or of drums, the report of artillery, rattle of 

 musketry, or the rumbling of a heavy waggon or train over a bridge ; 

 and after lasting several minutes, this noise is often followed by a 

 whistling sound, like that heard when a stone is thrown out of a 

 sling, which is caused by the rush through the air of the stone or its 

 fragments as it descends to the earth, into which it may bury itself 

 several yards if the ground be soft, or if meeting rock may be itself 

 shattered into fragments by the collision. The branches of trees are 

 often broken, and the decks of ships or roofs of houses penetrated, 

 and there are numerous instances of life having been lost, animals or 

 men having been struck down by the stones. Two monks were 

 thus killed at Cremona and Milan, in Italy ; and it is recorded that 

 an aerolite, weighing 8 lbs., falling on board ship at Eochfort, in 

 France, 1614, killed two Swedish sailors. 



The light emitted by" these fireballs or meteors is extremely bright, 

 especially by those which travel in a more oblique or horizontal direc- 

 tion. In some instances the light appears to have been even more power- , 

 ful than that of the sun, as objects have been known to throw shadows 

 in bright daylight when a meteor has been seen in the heavens ; more 

 generally it has been compared in brightness to that of a planet, or 

 to the electric or magnesium light, frequently, like the latter, leaving 

 a bright track or trail behind it remaining visible to the eye 

 for several seconds or minutes after the passage of the body icself. 

 Whether this is meiely an impression left on the retina, or ocular 

 deception, or is due to finel}^ divided highly incandescent s )lid 



