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TABLE OF "CONTENTS

SEPTEMBER, 1905

Page Cover Design by Ward & DELAY. Frontispiece. Portrait of RICHARD

TELLER CRANE, Founder and President of the Crane Company, ac

companying biographical sketch. How Eclipses are Predicted. By Prof.

DAVID P. Todd, Ph.D., Director of

Amherst College Observatory.. 1 People Will Talk. Poem . . : . 6 Oyster Farming. By Winifred FALES 7 Easy There! Poem ...... 14 How Eclipses are Studied. By C. H...

CLAUDY . . . . . . . . . 15 The World's Great Clocks. By Fritz

MORRIS . . . . . . . . . 21 A Little Song of Life. Poem. By

FRANK L. STANTON . . . . . Nebula. A Narrative. By EUGENE

S. BISBEE . . . . . . . . . The Beyond. A Poem. By Ella

WHEELER Wilcox . . . . . . Plane-Table Work in the Field. By HARRY L. Fair . . . . . . . .

40 Ocean Cables. By P. T. McGrath 49 Secret of Victory. By Sydney Smith 60 Making Electric Meters. By J. B.

BAKER, S. B. . . . . . . . Infant Incubators. By RUTLEDGE

RUTHERFORD . . . . . . . Ghosts. Poem . . . . . . . .

73

73 A Lost River. By William G. Fitz

GERALD . . . . . . . . . 74

JPage Log Rafts of the Pacific. By WALDON

FAWCETT . . . . . . . . .
Views from the Portland Fair. ..
Editorial Department
Metallic-Filament Incandescent

Lamps · · · · · · · · ·
Trade Schools . . . . . . .
American Automobiles Abroad ..

Railroad Industrial Bureaus... A Printing Telegraph Central Station.

By Frank C. PERKINS ..... Dinner-Pail Philosophy ...... Zeuner's Valve Diagrams. By Walter

S. LELAND, S. B. . . . ... . Life Stories of Successful Men. Rich

ard Teller Crane. By W. S. ROGERS You. Poem. By Helen M. QUINN 97 Where History Was Made .... Engineering Progress . ....... Chalk Talks. No. XIX. The Blast

Furnace. By Carl S. Dow, S. B. 104 Blowing Off Steam ...... Science and Invention ..... 108 Alternating-Current Problems. By

Prof. William Esty, S. B., M. A. 113 Personal and Miscellaneous . .. 116 Consulting Department ..'... 128 Literature ......... 136 Employment Department . . . . 138

68

THE TECHNICAL WORLD is a monthly magazine, published the fifteenth of each month, devoted to the problems of the technical and industrial world, and a treatment of all matters of interest in Applied Science

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GEIN C. THRER
Entered at the Post Office, Chicago, Ill., as second-class mail matter,

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The Technical World Magazine

- 1357

Volume IV

SEPTEMBER, 1905

No. 1

How Eclipses are Predicted Marvelous Precision and Absolute Foreknowl

edge of Astronomical Science
By PROFESSOR DAVID TODD, Ph. D.

Director, Amherst College Observatory

THAT unique New England poet, stant of occurrence—for many years

a compound of daring, whimsi- ahead
cality and genius, once wrote:
“Eclipses are predicted,

Periodic Occurrence
And Science bows them in."

The period or round of eclipses that True enough at the time Emily Dick- these early astronomers employed is still inson jotted down these lines, her state- useful to us. It is called the Saros, and its ment has become increasingly accurate length is 6,585} days, or 18 years 11:} during all the years following. As long days. Usually 41 eclipses of the sun will ago as the days of Thales, in the sixth happen in this period, and about ten of century before Christ, a periodicity in the them will be total ones. A Saros may return of eclipses had been discovered, so be taken as beginning at any time, and that their appearance could be roughly the nature of the eclipses occurring in foretold. Probably first noted by the any one period changes but slowly ; so Chaldeans, the greatest astronomers of that once we have the time and place and antiquity, it is not unlikely that the circumstances of all the eclipses in one Chinese had also found general methods Saros, we can predict all those of the of prediction as early as 2000 B. C., half- next half-century with confidence. fabulous incidents of their astrologers But not with great accuracy, for there perhaps tending to support this theory. are too many variable conditions entering

But from the first accurately foretold into the problem of the celestial machine. eclipse by Thales, 585 B. C., so closely as “this very year in which it did actually Operation of the Solar System occur,” to that of August 30th, 1905, The cosmos of the solar system is but methods, discoveries, and precision have a vast mechanism, and eclipses are but steadily advanced, until now it is possible the inevitable phenomena of its perfect to give all the circumstances of coming working. Compare it with the automatic eclipses-exact locality, duration, and in- contrivances of a modern Hoe printing

Copyright, 1905, by The Technical World Company

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