Part 2 — CHAPTER LIII ASTRONOMY

No greater homage has ever been paid to the progress of American science than when the planning and supervision of the astronomical section of the new Encyclopaedia Britannica was entrusted to the late Prof. Simon Newcomb, who was also the only American save Benjamin Franklin ever elected an associate of the French Institute. His death occurred some time before the Britannica was completed, but he had already finished the articles which he had undertaken personally to contribute, and read a great number of the other articles which had, at his suggestion, been assigned to eminent astronomers in various parts of the world. His famous hand-book, Popular Astronomy, has been translated into all the European languages, and into Japanese as well; but the unlimited resources in the way of collaboration which the editorial organization of the Britannica put at his disposal, enabled him to assemble in these volumes a complete body of astronomical knowledge which is the greatest of his educational achievements.

The making of a lens for a great telescope is the most difficult undertaking in all craftsmanship, and the mounting of the telescope itself a triumph of mechanical ingenuity. Yet the stars and planets have been guide-posts for the shepherd and the sailor throughout the ages, and have told the farmer when to sow and when to reap, and, even in our day, observations made by an amateur, through a common field-glass, have in more than one instance yielded results of serious value.

A Few Facts

Progress is from one point of view so slow that astronomers are now compiling 323data regarding fixed stars of which the motion cannot be deduced for centuries to come; yet some of the changes to be observed are so swift that solar prominences often rise at the rate of 350,000 miles an hour, and have been seen to rise to that height. The temperature of the sun’s envelope, 6000° C., greatly exceeds any that we can artificially create, and would convert into gas any substance we know; and for every unit of heat it sends to the earth, a hundred million other units, poured into space, are absolutely lost for any purposes of mechanical effect.

Astronomy deals with objects so minute that even a shooting star evolving, as it passes through our atmosphere, so much light that we can trace its course with the naked eye, may be no larger than a grain of sand; deals, too, with objects of so shadowy a nature that the white clouds in our sky are, in comparison, solid blocks; and deals, again, with distances and surfaces so vast that numerical description fails to convey any impression but one of confusion.

It is not easy to conceive, when we see a balloon in the air, the remainder that would exist if the bag, the car, and the cordage were all subtracted. There would be, until the gas mixed with the atmosphere, a sphere of gas. The stars, our sun included, seem to be masses of incandescent gas, possessing fairly definite boundaries, and not far from spherical in shape; the nebulae seem also to be masses of incandescent gas, irregular in form and having no clearly marked limits; even the nucleus of a comet is apparently not solid enough to be opaque; and as the four great planets also seem to be gaseous, it is probable that only the smaller bodies, like our earth, the moon, and Mars, are solid.

To the rule that we can handle none of the matter that originates beyond the limits of our atmosphere, the meteorites supply an exception. Seventy years ago, a mass of stone, cold and invisible, flying through the aether of space at the rate of some hundred thousand miles an hour, entered our atmosphere, became so hot, as the air’s friction checked its speed, that bits of its surface, fused to crust, flicked off and floated in the air, leaving a shining trail; then as its speed was reduced to some three hundred miles an hour, cooled until it was no hotter than a laundress likes her iron to be. At Mhow, in India, as it made a dent in the earth, it killed a man—the only man known to history who has died so uncanny a death. But near Wold Cottage, in Yorkshire, England, thirty years before, another meteorite had fallen only ten yards from a labourer; and only thirty years ago another arrived on a Yorkshire railway line, forty yards from a gang of platelayers. The largest meteoric mass known weighs about fifty tons, but most of them seem to have split in the course of their journey; and at Hessle, a hundred thousand fragments spread, like grapeshot from a giant gun, over an area of some thirty square miles. See Meteorite (Vol. 18, p. 262).

Life on Mars

Although the closest scrutiny has not discovered in any meteorite a shred of life, even the lowest, we obtain, from another source, and by a different method of observation, evidence—as yet inconclusive,—that not only life, but intelligent life exists beyond our planet. As in respect of other astronomical problems, the Britannica is singularly clear, impartial and authoritative in its treatment of this question. The article Mars (Vol. 17, p. 761) was written by Professor Newcomb, but Professor Percival Lowell contributes a summary of the recent investigations and deductions relating to Mars with which his name is associated. In 1877, Schiaparelli, adopting the old belief now abandoned by all astronomers, that oceans occupied the darker-coloured regions of Mars, observed dark streaks connecting these dark patches, and, believing them to be 324strips of water, described them by the Italian word “canale,” by which he meant channels, or natural bodies of water. An absurd misconception of his meaning gave wide currency to the idea that these strips were artificial canals, a manifest impossibility, as they are many miles in width. No canal, properly so called, could be so wide, and no reservoir could conceivably be so extensive. There is, in the existence of such patches, even if they were bodies of water, as no one now believes them to be, not the slightest indication of excavation. In 1894, Professor Lowell, an American astronomer of great authority, established, for the special purpose of observing Mars, the Lowell Observatory at Flagstaff, in Arizona, 7,250 feet above sea level, in singularly clear, dry air, equipped with a twenty-four-inch telescope. This observatory unquestionably commands greater penetration than any other, and Professor Newcomb says that the work there upon Mars “has been continued with such care and assiduity that its results must take precedence of all others.” Professor Lowell’s first announcement that he had detected evidences of the existence of extensive artificial canals, which would of course absolutely prove Mars to be inhabited by intelligent creatures, was received with derision by many critics who jumped to the conclusion that he meant artificial canals many miles in width. Fuller statements from Professor Lowell showed that he believed Schiaparelli’s wide strips to be not water, but areas of vegetation lying on each side of artificial irrigating canals of no extraordinary width, by a network of which water is brought to, and distributed throughout, the temperate and equatorial zones of Mars from the extreme North and South, as the polar snow caps melt; and that this irrigation gives the rainless area a seasonal fertility, just as the melting of Abyssinian snows fecundates the distant valley of the lower Nile. These strips, according to Professor Lowell and other observers, are at one season of a bluish-green colour suggesting prosperous vegetation, then fade to a paler shade or in some places to a tawny brown. The strips are thousands of miles in length, perfectly straight. No one claims to have seen the artificial canals, but if there are areas of vegetation, they must be due to irrigation performed by waterways. If continued observations confirm the existence of these strips, it will become certain that they are not telescopic illusions, but the results of engineering operations on a scale unknown to our planet. The readings indicated in this chapter will yield a survey of this special field, as of all other fields of current research in astronomy, and give new interest to current investigations.

A brief account of some of the principal astronomical articles is printed here in tabular form, and a fuller list, alphabetically arranged, follows this topical outline.

Topics for Reading Article and Contributor

Early Interest in the Sky.

Astral theology—the “assumption of a close link between the movements going on in the heavens and occurrences on the earth.” The history of astrology traced to ancient Babylonia (about 3000 B.C.). Astrology (Vol. 2, p. 795), and Babylonian and Assyrian Religion (Vol. 3, p. 114), by Dr. Morris Jastrow, author of Religion of the Babylonians and Assyrians.

Story of the Constellations. A Map of the Heavens. Constellation—with star-maps and tables (Vol. 7, p. 11), by Charles Everitt, fellow Royal Astronomical Society. See also separate articles on the principal constellations and stars.

325Development of Astronomy.

Scientific knowledge of the ancient Chinese, Egyptians and Babylonians. Revolutionary cycle of the planets. Astronomy, History (Vol. 2, p. 808), by Agnes M. Clerke, author of A Popular History of Astronomy.

First conception of the earth as a globe. “The harmony of the spheres.” Identification of morning and evening stars (about 520 B.C.). Pythagoras (Vol. 22, p. 699), by Dr. A. S. Pringle-Pattison, author of Man’s Place in the Cosmos, etc.

The Greeks measure the earth by astronomical means (about 200 B.C.). Eratosthenes of Alexandria (Vol. 9, p. 733), by Sir Thomas Little Heath, author of Treatise on Conic Sections.

The first observatory. Observatory (Vol. 19, p. 954), by J. L. E. Dreyer, Director of Armagh Observatory.

The first systematic astronomer, Ptolemy and his System (A.D. 150). Ptolemy, Mathematics (Vol. 22, p. 620), by Prof. George J. Allman, Queen’s, Galway; Copernicus (Vol. 7, p. 100), by Agnes M. Clerke.

Revival of heliocentric theory (A.D. 1506–1512). Kepler, Johann (Vol. 15, p. 749), by Agnes M. Clerke.

Plan of Solar System realized. The founder of descriptive astronomy (1564–1642). Galileo Galilei (Vol. 11, p. 406), by Agnes M. Clerke.

Newton’s contributions to astronomy and astronomical physics (1585–1586). Newton, Sir Isaac (Vol. 19, p. 586), by Henry M. Taylor, Fellow of Trinity College, Cambridge.

Continuation of Newton’s work. Euler, Leonhard (Vol. 9, p. 887).

Nebular hypothesis of Laplace (1796). Nebular Theory (Vol. 19, p. 333), by Sir Robert S. Ball, author of The Story of the Heavens, etc.

The New Astronomy.

Work of Wollaston, Fraunhofer, Kirchoff, and Rowland in spectrum analysis. Astrophysics (Vol. 2, p. 819), by Dr. Simon Newcomb, late director National Observatory, Washington.

Discoveries during recent eclipses. Photographing the Heavens, Star-charts, etc. Photography, Celestial (Vol. 21, p. 523), by Prof. H. H. Turner, Oxford, author of Modern Astronomy, etc.

Measuring light and heat from the stars,—radio-micrometer. Photometry, Celestial, or Stellar Photometry (Vol. 21, p. 530), by Dr. H. H. Turner, Oxford.

New method of photographing the sun and the results of this mode of study. Spectroheliograph, illustrated (Vol. 25, p. 618), by Dr. George E. Hale, inventor of the spectroheliograph.

Principles of Astronomy.

How the positions and motions of the heavenly bodies are defined. System of co-ordinates. Astronomy, Spherical or Geometrical Astronomy (Vol. 2, p. 801), by Dr. Simon Newcomb.

Distance of sun from earth the fundamental celestial measurement. Parallax (Vol. 20, p. 760), by Dr. Simon Newcomb.

326Methods of determining distances of stars. Star, Distances and Parallaxes of the Stars (Vol. 25, p. 789), by Arthur S. Eddington, Royal Observatory, Greenwich.

Apparent motion of the heavenly bodies. Aberration, Aberration of Light (Vol. 1, p. 54), by Dr. S. Otto Eppenstein, Zeiss Optical Works, Jena, Germany.

Eclipses and their recurrence. List of solar eclipses. Methods of computing eclipses. Eclipse (Vol. 8, p. 887), by Dr. Simon Newcomb.

Diameter of earth as an astronomical unit. Determination of diameter and figure of earth. Earth, Figure of the (Vol. 8, p. 801), by Alexander R. Clarke, Ordnance Survey, and Prof. F. R. Helmert, University of Berlin.

The Stars. The two Star-Streams. Milky Way. Distribution of stars. Star (Vol. 25, p. 785), by Arthur S. Eddington, Royal Observatory, Greenwich.

True nebulae. Constitution. How they differ from star-clusters. Nebula, illustrated (Vol. 19, p. 332), by Arthur S. Eddington.

Comets—origins and orbits. Physical constitution. List of periodic comets. Comet, illustrated (Vol. 6, p. 759), by Dr. Simon Newcomb.

Shooting Stars. History of meteoric showers. Meteor (Vol. 18, p. 260), by W. F. Denning, formerly president, Liverpool Astronomical Society.

Constitution of Shooting Stars. Meteorite (Vol. 18, p. 262), by Lazarus Fletcher, author of Introduction to the Study of Meteorites.

General description of the Solar System. Solar System (Vol. 25, p. 357), by Dr. Simon Newcomb.

The photosphere, chromosphere and corona, dimensions, temperature, and age of the sun, sun-spots. Sun, illustrated (Vol. 26, p. 85), by Dr. Ralph A. Sampson, Astronomer Royal for Scotland.

The vast envelope which surrounds the sun. Zodiacal Light (Vol. 28, p. 998), by Dr. Simon Newcomb.

Are Northern Lights due to emanations from the sun? Aurora Polaris, illustrated (Vol. 2, p. 934), by Dr. Charles Chree, president Physical Society of London.

Opaque Bodies, members of the Solar System. Their relation to each other. Their spectra, atmosphere, temperatures. First planetoid discovered (Jan. 1, 1801). Groupings of the planetoids. Planet, illustrated (Vol. 21, p. 714), and Planets, Minor (Vol. 21, p. 717), both by Dr. Simon Newcomb.

The smallest major planet. How it presents the same face always to the sun. Mercury (Vol. 18, p. 154), by Dr. Simon Newcomb.

Venus: Its peculiar rotation and cloudy atmosphere. Has Venus a satellite? Venus (Vol. 27, p. 1013), by Dr. Simon Newcomb.

The earth as a member of the solar system. Earth (Vol. 8, p. 799).

327Our nearest neighbour. Is it inhabited? Similarity of physical conditions to those of the earth. Mars, illustrated (Vol. 17, p. 761), by Dr. Simon Newcomb, with a summary by Professor Lowell, of the observations at Flagstaff.

The largest planet. Its belts, spots, markings and surface. Is the great red spot a floating island? Jupiter, illustrated (Vol. 15, p. 562), by W. F. Denning, formerly president, Liverpool Astronomical Society.

The ringed planet. Physical constitution of rings. Saturn (Vol. 24, p. 232), by Dr. Simon Newcomb.

Uranus: Its discovery, physical characteristics and satellites. Uranus (Vol. 27, p. 788), by Dr. Simon Newcomb.

The outermost known planet. Dimensions. Resemblance to Uranus. Neptune (Vol. 19, p. 385), by Dr. Simon Newcomb.

Wonderful story of its discovery (1845). Adams, John Couch (Vol. 1, p. 177). Leverrier, U. J. J. (Vol. 16, p. 510), by Agnes M. Clerke, author of A Popular History of Astronomy.

The moon. Its aspects, phases and constitution. Its mountains and atmosphere. Moon, illustrated (Vol. 18, p. 802), by Dr. Simon Newcomb.

Development of Practical and Observational Astronomy.

Current mode of star nomenclature adopted (1603). First planetary transit observed by Gassendi (1631). Astronomy, History of Astronomy (Vol. 2, p. 813), by Agnes M. Clerke, author of A Popular History of Astronomy.

Astronomical Instruments.

How co-ordinates used in astronomical research are determined. Astronomy, Practical Astronomy (Vol. 2 p. 807), by Dr. Simon Newcomb.

Telescope: Discovery and history. Parts and mounting. Great telescopes of the world. Telescope, illustrated (Vol. 26, p. 557), by Sir David Gill, formerly Astronomer Royal at the Cape of Good Hope, and H. Dennis Taylor, inventor of the Cooke Photographic Lens.

The Transit Circle due to Tycho Brahe. Description and use. Transit Circle, illustrated (Vol. 27, p. 181), by J. L. E. Dreyer, Armagh Observatory, author of Planetary Systems from Thales to Kepler, etc.

Measuring machines. Importance and use in astronomy. Micrometer, illustrated (Vol. 18, p. 381), by Sir David Gill.

Measuring the sun’s diameter. Heliometer, illustrated (Vol. 13, p. 224), by Sir David Gill.

Old time instruments. “Nearly every one of the modern instruments used for the observatories of practical astronomy is part of the perfected astrolabe.” Astrolabe, illustrated (Vol. 2, p. 795), by Lady Huggins, author of Life and Work of G. P. Mazzini.

Complete list of observatories throughout the world, date of foundation, their equipment and their specialized work. Observatory (Vol. 19, p. 953), by J. L. E. Dreyer, director Armagh Observatory, author of Planetary Systems from Thales to Kepler.

328

LIST OF ARTICLES IN THE ENCYCLOPAEDIA BRITANNICA ON ASTRONOMY

Aberration

Ablatitious

Adams, John Couch

Airy, Sir George B.

Albategnius

Albedo

Albumazar (Abu-Maaschar)

Algol

Alidade

Almacantar

Altitude

Amici, Giovanni B.

Amplitude

Andromeda

Andronicus of Cyrrhus

Anomaly

Ansa

Aphelion

Apse and Apsides

Aquarius

Aquila

Arcturus

Argelander, F. W. A.

Aries

Aristarchus, of Samos

Armilla

Astrolabe

Astrology

Astronomy

Astrophysics

Auriga

Azimuth

Bailly, Jean S.

Baily, Francis

Bainbridge, John

Bessel, Friedrich W.

Bianchini, Francesco

Binary System

Biquintile

Black Drop

Bode, Johann Elert

Boötes

Bradley, James

Brahe, Tycho

Brisbane, Sir Thomas M.

Brünnow, F. F. E.

Calvisius, Sethus

Campani-Alimenis, M.

Cancer

Canes Venatici

Canis Major

Capricornus

Carrington, R. C.

Cassini (family)

Cassiopeia

Celsius, Anders

Centaurus

Cepheus

Cetus

Chromosphere

Clerke, Agnes Mary

Colure

Coma Berenices

Comet

Comet-Seeker

Compression

Conjunction

Conon

Constellation

Copernicus, Nicolaus

Corona

Coronium

Cosmic

Culmination

Cunitz, Maria

Cycle

Cygnus

Cynosure

Declination

Dee, John

Deferent

Delambre, J. B. J.

De la Rue, Warren

Delisle, Joseph N.

Delphinus

Dial and Dialling

Dick, Thomas

Direct Motion

Diurnal Motion

Donati, Giovanni B.

Draco

Dupuis, Charles F.

Earth

Eccentric

Eclipse

Ecliptic

Egress

Ellipticity

Elongation

Encke, Johann Franz

Ephemeris

Epicycle

Epoch

Equation of the Centre

Equation of Time

Equator

Equinox

Eratosthenes of Alexandria

Eridanus

Eros

Establishment of a Port

Evection

Facula

Firmament

Flamsteed, John

Galileo, Galilei

Gegenschein

Gemini

Geocentric

Gould, B. A.

Grant, Robert

Halley, Edmund

Hansen, Peter Andreas

Hansteen, Christopher

Heliacal

Heliocentric

Heliometer

Hercules

Herschel, Caroline L.

Herschel, Sir F. W.

Herschel, Sir J. F. W.

Hevelius, Johann

Hipparchus

Horizon

Horrocks, Jeremiah

Hour Angle

Huggins, Sir William

Hydra

Ideler, C. L.

Immersion

Inghirami, G.

Ingress

Invariable Plane

Janssen, Pierre Jules C.

Jupiter

Kepler, Johann

Lacaille, N. L. de

Lalande, J. J. L. de

Lamont, Johann von

Latitude

Lemonnier, Pierre C.

Leo

Leverrier, U. J. J.

Libra

Libration

Lilly, William

Lockyer, Sir J. Norman

Longitude

Longomontanus, C. S.

Lunation

Lyra

Magellanic Clouds

Mars

Mayer, Johann Tobias

Mercury

Meridian

Meteor

Metonic Cycle

Micrometer

Mitcel, Ormsby M.

Mitchell, Maria

Möbius, August F.

Moon

Mouchez, A. E. B.

Nadir

Nebula

Nebular Theory

Neptune

Newcomb, Simon

Node

Nostradamus

Nutation

Observatory

Occultation

Olbers, Heinrich W. M.

Orbit

Orion

Parallax

Penumbra

Perigee

Perihelion

Perseus

Phoebe

Photography, Celestial

Photometry, Celestial

Piazzi, Giuseppe

Pickering, E. C.

Pisces

Planet

Planets, Minor

Pleiades

Pond, John

Pons, Jean Louis

Precession of the Equinoxes

Prime Vertical

Pritchard, Charles

Proctor, Richard A.

Ptolemy (Claudius)

Quadrature

Quetelet, L. A. Jacques

Ramsden, Jesse

Regiomontanus

Reichenbach, G. von

Repsold, Johann G.

Retrograde

Rheticus, or Rhaeticus

Right Ascension

Rittenhouse, David

Robinson, J. T. R.

Roemer, Ole

Rosse, William Parsons, 3rd earl of

Rümker, C. L. C.

Sabine, Sir Edward

Sacro Bosco, Johannes de (John Holywood)

Sagitta

Sagittarius

Santini, Giovanni

Satellite

Saturn

Schiaparelli, G. V.

Schönfeld, Eduard

Schröter, Johann H.

Schumacher, H. C.

Schwabe, Samuel H.

Scorpio

Secchi, Angelo

Serpentarius or Ophiuchus

Sextant

Smyth, Charles Piazzi

Solar System

Solstice

Somerville, Mary

Sosigenes

Spectroheliograph

Star

Stationary

Stone, Edward Jones

Struve, E. G. W.

Sun

Synodic Period

Syzygy

329Taurus

Telescope

Terminator

Three Bodies, Problem

Tide

Time, Measurement of

Time, Standard

Tisserand, F. F.

Transit Circle, or Meridian Circle

Trepidation

Troughton, Edward

Ulugh Beg

Umbra

Uranus

Ursa Major

Ursa Minor

Venus

Vertical

Virgo

Vulpecula et Anser

Walker, Sears Cook

Walther, Bernhard

Zach, Baron von

Zenith

Zodiac

Zodiacal Light

Zöllner, J. K. F.