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504

PAGE

Grammar, Criticism of Mr. Waters's Ar-
ticles on, J. 1. Thompson....

253

Happiness, The Highest, Ruric N. Roark.. 509

Helps, Hints and Suggestions.....

28, 75, 128, 170, 214, 269, 316, 465, 511, 551, 599

Hinsdale's Teaching of the Language Arts,

Charles Haupert

125

History, How Should a Busy Man Study,

Harry Pratt Judson....

590

History in the 0. T. R. C. for 1900-01,

Something About, J. J. Burns..

Hot Ice, J. A. Culler....

105

In the spirit, T. S. Lowden.

150

January

28

July

316

June

269

Lesson Story, Ruric N. Roark..

546

Library, The Traveling – Its Adaptability

to State and Local Conditions, C. B.

Galbreath

490

Lightning, A Stroke of, J. A. Culler.. 454
Lincoln's Gettysburg Speech..

77

Macaulay, J. J. Burns..

543

Machine, A, J. A. Culler..

244

March

128

May

214

Membership Roll

422

Minutes of General Association..

426

Minutes of Department of Superintendence 428
Moral Culture, Stages in, R. G. Boone.... 351
Morgan, William H., S. T. Logan..

84

Morgan, William H., George F. Sands.... 417

Nature Notes, No. 2, J. J. Burns..

24

Nature's Silences, J. A. Culler.

295

Nature Study, Caroline H. Parker........ 154

Necrology, Report of Committee on, W.

W. Ross

416

Newspaper, The Popular Literary (?), W.

G. Compher

289

Normal Schools, Emerson E. White.. 223
Notes of an Ohio Student Abroad, Some,
R. C. Super...

193
Notes, Introductory, J. J. Burns..463, 503, 590
November

551

October

511

Ohio, Geography and History of, F. B.

Pearson....15, 115, 164, 249, 298, 458, 500, 587

Opening Exercises, Some Plans for, Mar-
garet W. Sutherland...

........171, 215, 269
Over-Study in the Public Schools, J. J.
Bliss

97

0. T. R. C..

.21, 69, 123,

166, 206, 265, 310, 418, 463, 503, 543, 590
Pedagogical Landscape, The, B........... 21
Picture Study, S. H. Layton...

160
Population of Cities in 1900.

605

Primary Work, Mary Gordon..

340

Prizes for Onio School Boys and Girls,

Valuable

521

PAGE

Proceedings of the Different Sections,

Summary of the.....

421

Program, A Thanksgiving, Margaret W.

Sutherland

551

Promotions, A Rational System of, Frank

J. Roller

385

Psychology and the Teacher, Clark Wiss-

ler

241

Questions, County Examination..514, 559, 610

Questions for Mr. Culler, Some, Carl C.

Marshall

163

Questions, State Examination.... ..56, 446

Questions on Oman's England, Sugges-

tive

....506, 549, 597

Questions on Judson's Europe, Sugges-

tive

..508, 550, 598

Rallying Song, Teachers', Venable and

wantvoort

468

Rambling Notes, J. J. Burns.

.69, 168

Reading, W. H. Lole..

53

Reply to Mr. Marshall, J. A. Culler...... 201

Reply to Mr.Thompson, A. F. Waters... 461

Resolutions, Report of Committee on...... 420

Rock Floor of Ohio and Its Development,

The, J. A. Bownocker.....

145

Rhythm, A Practical Lesson in, J. J.

Burns

172

School Curriculum, Limitations of, F. S.

Coultrap

374

School Curriculum, Limitations of, Arthur
Powell

380

School Hygiene, Prize Essays on...

228

School Management, Hints on, Margaret

W. Sutherland

75

Science Teaching in the Public Schools,

Report of Committee on, W. A. Keller-

120

Self-Training of the Teacher, The, Mary
Wilgus

401
September

465
Should Elementary Natural Science be

Taught in the Country Schools? George
H. Lapp...

306

State Normal Schools, John E. Morris.. 49, 394

State Normal Schools for Ohio, R. S.

Thomas

51

Steamship, The Largest in the World.... 316

Suggestion in Early Euucation, Daniel

Putnam

21

Suggestion in Life and Society, Daniel
Putnam

70
Teaching English, Quotations on, Charles
Haupert

166

Thackeray, Margaret W. Sutherland.... 593

Township High Schools, S. K. Mardis.... 398

Trip to California, Notes on a, J. P. Gordy 100

Washington, Tributes to.....

Weight, J. A. Culler....

5

What We Lack, W. H. Wisman.

264

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By FRANK G. CARPENTER, author of "ASIA” and “NORTH AMERICA.” Traveler and newspaper correspondent. A fascinating book of travel, profusely illustrated, with photographs by the author.

“SOUTH AMERICA," just issued, contains

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Maps..

8 Illustrations.
Colombia ....

Across the Isthmus of Panama..
Ecuador
Peru

In Lima, the Capital ....

On the Roof of South America
Bolivia
Chile.....

A Visit to a Chileau Farm

At the End of the Continent.
Argentina

Life on the Pampas.
Uruguay
Paraguay

A Trip to the Interior
Brazil ....

In the Land of Coffee..

Up the Amazon
Venezuela
Guiana ...

210
11 Pages
11
12
14

8
15
22
46
7
9
24

8 15 17

7 62 10 12 15 9

Single copies of any of our publications witl be sent by mail, postpaid, on
receipt of the price. Special terms for first introduction. Correspon-
dence is cordially invited.

AMERICAN BOOK COMPANY,

317 Walnut Street, Cincinnati, Ohio.

New York
Chicago

EXC: GE
CLEVELAND PUBLIC LIBRARY

Pipelir berary, JAN 8/1900 Who JUL

Branche

[blocks in formation]

THE PROBABLE AGE OF THE EARTH, AND HOW

IT IS DETERMINED.

BY J. A. BOWNOCKER.

Aside from the origin of the rocks (sandstones, limestones, earth there is perhaps no question shales, etc.); while Sir Alfred R. relating to our planet of more gen- Wallace thought 28,000,000 years eral interest than its age. At the sufficient time to allow. Some outset let it be understood that we years ago Professor Alexander can not hope to make anything like Winchell announced 3,000,000 an exact statement of this, and that years as the time required, this bewe must content ourselves with a ing the lowest geological estimate rough approximation.

of 'which the writer has knowTo determine this estimate we ledge. In 1893 Mr. C. D. Walcott, have at present two methods, one the director of the United States of these may be styled the Geo- geological survey, announced 45,logical, since it is based on data 000,000 as the time necessary for pertaining to that science; and the the formation of the sedimentary other the Physical, because it uses rocks; and in the same year Mr. the principles of Physics. How W. J. McGee stated that in his these estimates are actually made opinion, 6,000,000,000 years are will be stated later in this paper.

necessary. These

These figures show Let us first examine the estimates two things: (1) That geologists themselves, as made by the follow- themselves vary greatly in their esers of these two sciences.

timates of the age of the earth;

and (2) that our planet is very old, THE GEOLOGISTS' ESTIMATES.

for if the smallest of the above James Croll thought 72,000,000 figures should be adopted even years have elapsed since the depo- then our planet would have an ansition of the first sedimentary tiquity greater than would have

ter.

ac

or

been thought possible a few gener- examined, it will be found that ations ago.

those of the former are generally THE PHYSICISTS' ESTIMATES. much larger than those of the latLord Kelvin, who has taken the

In fact until comparatively lead in this mode of computations,

recent years geologists were announced in 1862 that the crust of

customed to deal with time as of

unlimited extent. If 100,000,COO the earth could not have been formed less than 20,000,000 years

years sufficed for the production of ago nor more than 400,000,000

a certain phenomenon, very good; years ago. At the same time he but if it did not, then this period

trebled. stated that 100,000,000 would be might be doubled sufficient to include the total geo

Thus it happened that the geolological history of our planet. But

gist became accustomed to dealing later, after reviewing the evidence,

with vast periods, and time became he announced that only about 20,

to him an important item of his

stock in trade. 000,000 years could be granted. Professor Tait still further restricts

But in the sixties the physicist geological time, and can not allow began to call a halt to these heavy more than 10,000,000 years. Pro

demands on the “bank of time." fessor Simon Newcomb, the emi

Instead of geological time being of nent American astronomer, states

unlimited extent it was declared to that owing to the great heat of the be just the reverse; and while it is early crust water in the liquid doubtless very long when judged form has not existed on our planet by human standards, it is nevermore than 10,000,000 years, and he

theless short when compared to estimates the age of the solar sys

the periods demanded by the geoltem at about 20,000,000. Profes- ogists. Not

content, however, sor George Darwin has computed with this general restriction, the that the moon separated from the physicist has made reduction after earth about 57,000,000 years ago,

reduction in his estimates, until and since this happened while the

the time allowed for the evolution planet was still in a liquid condi- of our planet appears altogether intion it was long before the begin- adequate to the geologist. ning of geological time, which, we While these restrictions may say, dates from the formation hardly be accepted by the geoloof a solid crust.

gist, it must be admitted that they HOW THE PHYSICIST HAS CHECKED

have performed a useful service in THE GEOLOGIST.

restraining him from the use of If the estimates of the geolo- vast ages for which there is neither gists and physicists just named be authority nor necessity.

can

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