It is a pleasant duty to acknowledge here my obligations to the U. S. Signal Corps, the Smithsonian Institution, and the U. S. Weather Bureau, for much assistance in collecting the materials for this work. Dr. W. J. Humphreys, of the U. S. Weather Bureau, has very kindly read the manuscript for the chapters on the atmosphere.

My thanks are due also to the Scientific American and to Aëronautics for the use of photographs for the illustrations, as also to the manufacturers of various aircraft, and to Mr. W. J. Hammer, Mr. Carl Dientsbach, and Mr. A. S. Levino.

A. F. Zahm.

Cosmos Club
Washington, D. C.,
January, 1911.

CONTENTS

CHAPTER

PAGE

INTRODUCTION

[Introduction]

3

PART I

GROWTH OF AËROSTATION

I.

—[Early History of Passive Balloons]

29

II.

—[Practical Development of Passive Balloons]

54

III.

—[Early History of Power Balloons]

78

IV.

—[Introduction of Gasoline-Driven Dirigibles]

101

V.

—[Practical Development of Non-Rigid Dirigibles]

115

VI.

—[Development of Rigid Dirigibles]

145

PART II

GROWTH OF AVIATION

VII.

—[Model Flying Machines]

173

VIII.

—[Nineteenth Century Man-Flyers]

202

IX.

—[Aëroplanes of Adequate Stability and Power]

235

X.

—[Advent of Public Flying]

256

XI.

—[Strenuous Competitive Flying]

283

XII.

—[Forcing the Art]

307

PART III

AËRONAUTIC METEOROLOGY

XIII.

—[General Properties of Free Air]

347

XIV.

—[General Distribution of Heat and Pressure]

363

XV.

—[Permanent and Periodic Winds]

376

XVI.

—[Cyclones, Tornadoes, Waterspouts]

394

XVII.

—[Thunderstorms, Wind Gusts]

422

APPENDICES

I.

—[Stress in a Vacuum Balloon]

443

II.

—[Aëronautic Letters of Benjamin Franklin]

446

III.

—[Successful Military Dirigible Balloons]

456

IV.

—[The Relations of Weight, Speed, and Power of Flyers]

478

V.

—[Curtiss’ Hydro-Aëroplane Experiments]

481

[INDEX]

487

LIST OF PLATES