Problem of assimilation: Why national unity is indispensable to secure perpetuity of our institutions; to prevent foreign aggression; in any time of stress lines of cleavage tend to open. Forces that unite men, common race or descent; language; religion; habits; ideas; ideas most powerful. How can these be secured?

Common race: Secured by intermarriage; rapidity of this movement in America. Problem of cross-breeding; breeding in-and-in disastrous; slight differences advantageous; great differences disastrous: Negroes, Asiatics and Hebrews difficult to assimilate, latter because of objection to intermarriage.

Common language: Secured by all learning English; tenacity with which people cling to language; Wales, Swiss cantons, Cyprus. Our problem, Spaniards in Southwest; French in Northeast; Slavs in mining districts; foreign colonies in great cities; efforts of foreign patriotic societies to preserve their speech; not a serious problem at present, though 1,500,000 people in America do not know English.

Common religion: Secured by toleration; agreement in diversity. Groups difficult to assimilate: Catholics, Mormons, Hebrews, Lutherans.

Common habits of life: Easily secured where settlers are separated; attrition of neighborhood life wears out peculiar customs, costumes, manners, and observances.

Common ideas: The strongest force today; secured through schools, reflex action of the school upon the home; newspapers; festivals, Fourth of July; common enthusiasms, Washington, Lincoln, Civil War.

New conditions prevailing in United States: Free lands exhausted, though great tracts are uninhabited; hence present immigrants settle together in cities. New races are coming; Western Europe, England, Ireland, Scandinavia, Germany, France, in 1869 sent us 74 per cent of our immigrants, now 20 per cent. At present arrivals are mainly from Southeastern Europe-Italians, Poles, Russians, Hungarians; more difficult to Americanize these races. Basis of selection now

mainly industrial; formerly, often political and religious persecution.

Present tendencies towards restriction: Chinese excluded; Europeans must have health, money, character, intelligence. Reaction of colonies and United States on Europe: Experiment stations in political and social life; in industry; and in education. Consciously seek to change European conditions, Irish in America; invade Europe and European markets as travelers and as traders,

READING.

Annual Reports of the Commissioner-General of Immigration. Mayo-Smith, Richmond. Emigration and Immigration. Scribners: New York. 1892.

Restriction of Immigration. In Discussions in

Walker, Francis A.
Economics and Statistics.
Woods, Robert A.
& Co.: Boston.

1902.

1899.

Henry Holt: New York.
Americans in Process. Houghton, Mifflin

TOPICS FOR DISCUSSION.

1. What will be the American type in 2000 A. D.? 2. How far is free trade in men desirable?

UNIVERSITY EXTENSION LECTURES

SYLLABUS

OF

A Course of Six Lectures

ON

THE SOLAR SYSTEM

BY

SAMUEL ALFRED MITCHELL, A.M., PH.D.

TUTOR IN ASTRONOMY, COLUMBIA UNIVERSITY, LECTURER FOR THE AMERICAN SOCIETY FOR THE EXTENSION OF UNIVERSITY TEACHING

THE SOLAR SYSTEM

INTRODUCTORY NOTE

To get the greatest benefit from the course, considerable reading should be done before each lecture. The following books of reference may be consulted:

YOUNG, General Astronomy.

NEWCOMB, Popular Astronomy.

HowE, Elements of Descriptive Astronomy.

LANGLEY, The New Astronomy.

CLERKE, FOWLER AND GORE, Astronomy.

BALL, The Story of the Heavens.

CLERKE, History of Astronomy during the Nineteenth Century

(edition of 1902).

YOUNG, Manual of Astronomy.

YOUNG, The Sun.

COMSTOCK, A Text-Book of Astronomy.

WEBB, Celestial Objects for Common Telescopes.

BALL, Starland.

CHAMBERS, Story of the Stars.

CHAMBERS, Solar System.

Those attending the course are invited to send written answers to the questions at the end of each chapter; they should be addressed to Dr. S. A. Mitchell, Columbia University, New York City, and should arrive fully forty-eight hours before the following lecture. These will be returned at the class, when further explanations on the general subject will be made.

LECTURE I
THE SUN

The Distance of the Sun: To get a correct idea of the Sun, it is first of all necessary to find its distance from the Earth. This problem is one of the most important, as well as one of the most difficult in the whole science of Astronomy. Its importance lies in the fact that the Earth-Sun distance is the astronomical unit of length, and all celestial distances, ex1 May serve as text-book of the course.