The Wonder Book Of Knowledge Part 73

[11] Ill.u.s.trations by courtesy of R. Hoe & Co.

[12] Ill.u.s.trations by courtesy of the A. I. Root Co.

[13] Ill.u.s.trations by courtesy of the Hotpoint Electric Heating Co.

[14] Ill.u.s.trations by the courtesy of the American Telephone and Telegraph Co.

[15] Ill.u.s.trations by courtesy of the Otis Elevator Co.

[16] Ill.u.s.trations by courtesy of the International Silver Co.

[17] Ill.u.s.trations by courtesy of the McClure Co.

[18] Ill.u.s.trations by courtesy of New York Edison Co., unless otherwise indicated.

[19] Ill.u.s.trations by courtesy of The Curtis Publis.h.i.+ng Co.

[20] Courtesy of George A. Hormel & Co.

[21] Courtesy of The Field, New York City.

[22] Courtesy of The Field, New York City.

[23] Courtesy of the California Redwood a.s.sociation.

[24] Ill.u.s.trations by courtesy of The Brunswick-Balke-Collender Co.

[25] Ill.u.s.trations by courtesy of the American Pin Company.

[26] Ill.u.s.trations by courtesy of the Common Sense Gum Co. Story by courtesy of the American Chicle Co. and the Common Sense Gum Co.

[27] Ill.u.s.trations by courtesy of The Brunswick-Balke-Collender Co.

[28] Ill.u.s.trations by courtesy of the Addressograph Co.

[29] Ill.u.s.trations by courtesy of the Pyrene Manufacturing Co.

[30] Ill.u.s.trations by courtesy of Gatchel & Manning.

[31] Courtesy of Mr. Charles L. Trout.

[32] Ill.u.s.trations by courtesy of the Bethlehem Steel Co.

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[39] Ill.u.s.trations by courtesy of the Bethlehem Steel Co.

[40] Ill.u.s.trations by courtesy of the Bethlehem Steel Co.

[41] Ill.u.s.trations by courtesy of the Bethlehem Steel Co.

[42] Ill.u.s.trations by courtesy of the Bethlehem Steel Co.

[43] Ill.u.s.trations by courtesy of the Bethlehem Steel Co.

[44] Ill.u.s.trations by courtesy of the Bethlehem Steel Co.

[45] Ill.u.s.trations by courtesy of the Bethlehem Steel Co.

[46] Ill.u.s.trations by courtesy of United Shoe Machinery Co.

[47] Courtesy of James Boyd & Bro., Inc.

[48] Courtesy of American LaFrance Fire Engine Co.

[49] Courtesy of American LaFrance Fire Engine Co.

[50] Courtesy of American LaFrance Fire Engine Co.

[51] Courtesy of American LaFrance Fire Engine Co.

[52] Ill.u.s.trations by courtesy of American Cyanamid Company.

[53] Courtesy of The Strauss Bascule Bridge Co.

[54] Courtesy of The American Magazine.

[55] _Ill.u.s.trations by courtesy of the Railway Age Gazette and Standard Steel Car Co._

[56] Ill.u.s.trations by courtesy of Diamond Crystal Salt Co.

[57] Ill.u.s.trations by courtesy of the General Motors Truck Co.

[58] Ill.u.s.trations by courtesy of Jacobs & Davies, Engineers.

[59] Ill.u.s.trations by courtesy of Ford Motor Co.

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