30 AEROLITES 



stooping position ; tho handle being from twenty-four to thirty inches long, and the' 

 weight of the blade from two to four pounds. The adze is swung in a circular path 

 almost of the same curvature as tho blade, tho shoulder joint being the centre of 

 motion, and tho entire arm and tool forming, as it were, one inflexible radius ; the 

 tool, therefore, makes a succession of small arcs, and in each blow tho arm of the 

 workman is brought in contact with the thigh, which serves as a stop to prevent 

 accident. In coarse preparatory works, the workman directs his adze through the 

 space between his two feet ; he thus surprises us by the quantity of wood removed ; 

 in fine works ho frequently places his toes over the spot to be wrought, and the adze 

 penetrates two or three inches beneath the sole of tho shoe ; and he thus surprises us 

 by the apparent danger, yet perfect working of the instrument, which, in the hands 

 of a shipwright in particular, almost rivals the joiner's plane ; it is with him the 

 nearly universal paring instrument, and is used upon works in all positions. Holt- 

 zapffel. 



JEOIiIAN HARP. A musical instrument ; the invention of Kircher ; although 

 it was probably indicated by Hero of Alexandria. The musical sounds are produced 

 by the action of a current of air upon strings placed above a long box of thin deal. 

 The wires of the electric telegraph on the sides of our railroads are frequently set in 

 such a state of vibration by tho wind, that they become gigantic 2Eolian harps. 



AERATED WATER. The common commercial name of water artificially 

 impregnated with carbonic acid or oxygen. 



AEROZiXTES. Meteoric stones. It has long been well established that masses 

 of solid matter have fallen from the atmosphere upon this earth. Various hypotheses 

 have been proposed to account for them ; amongst others the following may be 

 named : 



1. That they are aggregations of solid matter which take place in the higher 

 regions of the air. It is known, however, that our atmosphere does not contain the 

 chemical elements of meteorites ; and, moreover, the large size of many of these 

 meteoric masses some weighing several tons each renders it extremely improbable 

 that they should be formed by condensation or aggregation in a highly attenuated 

 atmosphere. 



2. That they are projected from volcanoes in the moon. The researches of 

 Nasmyth, Smyth, and others appear to show that our satellite, whatever may have 

 been her condition at one period, is now in a state of comparative, if not of perfect, 

 repose. Some astronomers think they have observed changes in some parts of the 

 moon's surface, but there are no indications sufficiently clear to warrant the assump- 

 tion of there being any volcanoes in a state of activity. 



3. That belts composed of fragments of matter circulate in certain fixed orbits 

 around the sun, and that these fragments, sometimes entering our atmosphere, are 

 involved in the earth's influences, and fall in obedience to the law of gravitation. 

 The flights of ' shooting stars ' which are observed at particular periods appear to 

 favour this view. 



It has not been proved, however, that meteorites move in circumsolar orbits ; and 

 indeed evidence may be adduced tending to show that they have probably come from 

 regions of space beyond the limits of the solar system. 



It is usual to distinguish between aerolites, or meteoric stones, and siderif.es, or 

 masses of meteoric iron ; but tho two classes pass into each other through certain 

 meteorites, termed siderolites, which are partly metallic and partly stony. An 

 aerolite, or meteoric stone, is composed of a number of crystalline minerals, usually 

 loosely aggregated, and presenting a peculiar spherular structure. The surface of 

 the stone is invariably coated with an incrustation, in most cases lustrous and of a 

 black colour. This crust seems to be tho result of superficial fusion consequent upon 

 tho great development of heat due to the resistance which the stone suddenly encoun- 

 ters on entering the earth's atmosphere. 



Among the minerals found in aerolites may be noticed olivine and augite (two 

 silicates of magnesia), several alloys of iron and nickel, troilite (sulphide of iron), 

 schreiborsite (phosphide of iron and nickel), graphite, and certain hydrocarbons 

 similar to what are commonly regarded as organic compounds. The following average 

 per-centage composition of an aerolite has been calculated, by Reichonbach, from a 

 very large number of trustworthy analyses : silica, 40 ; iron, 25 ; magnesia, 20 ; 

 alumina, 2; sulphur, 2; nickel, 1*5; lime, 1*5; chromium, 0'5 ; manganese, 0'33 ; 

 sodium, 0'33 ; other elements, 1*34 ; oxygen, hydrogen, and loss, 5'5. 



Some interesting experiments on the artificial formation of meteorites have been 

 carried out, within the last few years, by M. Daubree. This chemist has been 

 successful in producing, on a small scale, certain products strongly resembling 

 meteorites, both in structure and composition. The artificial aerolites were produced 

 by fusing a rock called Lherzolite, the fusion being effected either alone or in the 



