The analysis of the spectrum, which is an image of white light passed through a prism, and refracted and decomposed into various colors of light is what scientists mean by the term spectrum analysis. The light of the sun and stars has been examined by spectrum analysis, and these heavenly bodies have thus been shown to contain some of the same elements as those which exist on the earth. Spectrum analysis has also, been usefully employed in physiology and pathology, and for the discovery of metals, etc.

One of the most wonderful discoveries in science that have been made, is the fact that a beam of light produces sound. A beam of sunlight is thrown through a lense on a glass vessel that contains lampblack, colored silk or worsted, or other substances. A disk, having slits or openings cut in it, is made to revolve swiftly in this beam of light, so as to cut it up, thus making alternate flashes of light and shadow. On putting the ear to the glass vessel strange sounds are heard so long as the flashing beam is falling on the vessel.

A term which has been occasionally abused in English popular writing is biology, more especially in the absurd word electro-biology, which at one time threatened to take root in popular usage, and has even by some scientific writers been confused with general physiology, or a special province of it. Yet the established and only legitimate meaning of biology is its literal one, that of the science of life - ie. the science which seeks to classify and generalize the vast and varied multitude of phenomena presented by and peculiar to the living world.

The Stoics were a school of philosophers who followed immediately after Plato and Aristotle. It was founded by Zeno of Citium (340-260 B. c), who taught in the painted portico (Stoa poikile) on the north side of the market place at Athens. The Stoics taught that God is the soul of the world, and that man's supreme good consists in living in accordance with the perfect life of the universe. For two hundred years all the best of the Romans were Stoics.

St. Elmo's Fire is the popular name of an electric appearance sometimes seen, especially in southern climates during thunder-storms, of a brush or star of light at the tops of masts, spires, or other pointed objects. It is also observed at the tops of trees, on the manes of horses, and occasionally about human heads. It is similar in kind to the luminous glow seen at the point when a lightning-rod is working imperfectly, or when there is any very rapid production of electricity.

In the human body there is said to be more than two million perspiration glands communicating with the surface by ducts, having a total length of some ten miles. The blood contains millions of millions of corpuscles, each a structure in itself. The number of rods in the retina, supposed to be the ultimate recipient of light, is estimated at thirty-million. A German scientist has calculated that the gray matter of the brain is built of at least six hundred million cells.

The word Arctic means property, lying near the constellation of the Bear (Gr. arctos) or Ursa Major, and hence, northern. The Arctic Circle is a circle drawn round the North Pole, at a distance from it equal to the obliquity of the ecliptic, or 23½°. The corresponding circle round the South Pole is the Antarctic Circle. Within each of these circles there is a period of the year when the sun does not set, and another when he is never seen, this latter period being longer the nearer to the pole. The word is also used figuratively to express extreme cold.

The Ignis Fatuus (Lat. ignis, "fire," fatuus, "foolish") is aluminous appearance of uncertain nature which is occasionally seen in marshy places and churchyards. The phenomenon has been frequently described, but it has been observed so rarely in favorable circumstances by scientific men that there is no satisfactory explanation. The light usually appears in autumn evenings shortly after sunset; it is common in the north of Germany, in Italy, in the south and north west of England, and on the west of Scotland, but it has been noticed in many other countries.

A device of modern science called the bottle chart is one which purports to show the track of sealed bottles thrown from ships into the sea. Lieutenant Becher, an English naval officer, constructed in 1843 a chart of bottle-voyages in the Atlantic, so as to illustrate the currents. The time which elapses between the launching of the bottle from the ship and the finding it on shore, or picking up by some other ship, has varied from a few days to sixteen years; while the straight-line distance between the two points has varied from a few miles to five thousand miles.

Somnambulism (Lat. somnus, ' 'sleep," ambulo, "I walk") is a disorder of sleep. It is symptomatic of more or less activity in some of the psychical and motor areas of the brain, while the centers that preside over consciousness are slumbering soundly. There are different forms, as sleep-crying, sleep-talking (somniloquy) and sleep-walking. These all involve sensori-motor acts. Sleep-walking is closely related to hysteria and epilepsy, and it occasionally alternates with these and allied diseases. It occurs mostly in youth, affecting males and females in almost equal proportion; commonly, although not invariably, it disappears when adult age is attained. It is met with chiefly in persons of nervous temperament.

A Vienna scientist has made a series of interesting experiments with the virus of such insects as bees and wasps, and comes to the conclusion that the effectiveness of the irritating substance depends largely upon the mood of the insect. A drop of the fluid taken from the poison bag of a dead hornet, for instance, produces a slight itching, but nothing resembling the inflammation caused by a hornet sting with a much smaller quantity of the same virus. This theory is supported by the curious fact that under the influence of rage the saliva of all sorts of otherwise harmless animals can become virulent enough to produce alarming and even fatal symptoms. Death from blood poisoning has more than once resulted from the bite of a wounded squirrel, a chipmunk or a caged rat.