[Transcriber's Note: Underscores are used as delimiter for _italics_. Small capitals have been transcribed as all capitals.] BOYS' SECOND BOOK OF INVENTIONS [Illustration: G. Marconi] BOYS' SECOND BOOK OF INVENTIONS BY RAY STANNARD BAKER _Author of Boys' Book of Inventions, Seen in Germany_ [Illustration] FULLY ILLUSTRATED [Illustration] NEW YORK DOUBLEDAY, PAGE & COMPANY MCMIX _Copyright, 1903, by_ McCLURE, PHILLIPS & CO. Published, November, 1903, N TABLE OF CONTENTS CHAPTER I PAGE THE MIRACLE OF RADIUM 3 Story of the Marvels and Dangers of the New Element Discovered by Professor and Madame Curie. CHAPTER II FLYING MACHINES 27 Santos-Dumont's Steerable Balloons. CHAPTER III THE EARTHQUAKE MEASURER 79 Professor John Milne's Seismograph. CHAPTER IV ELECTRICAL FURNACES 113 How the Hottest Heat is Produced--Making Diamonds. CHAPTER V HARNESSING THE SUN 153 The Solar Motor. CHAPTER VI THE INVENTOR AND THE FOOD PROBLEM 173 Fixing of Nitrogen--Experiments of Professor Nobbe. CHAPTER VII MARCONI AND HIS GREAT ACHIEVEMENTS 207 New Experiments in Wireless Telegraphy. CHAPTER VIII SEA-BUILDERS 255 The Story of Lighthouse Building--Stone-Tower Lighthouses, Iron Pile Lighthouses, and Steel Cylinder Lighthouses. CHAPTER IX THE NEWEST ELECTRIC LIGHT 293 Peter Cooper Hewitt and his Three Great Inventions --The Mercury Arc Light--The New Electrical Converter--The Hewitt Interrupter. LIST OF ILLUSTRATIONS Page Guglielmo Marconi _Frontispiece_ M. Curie Explaining the Wonders of Radium at the Sorbonne 5 Dr. Danlos Treating a Lupus Patient with Radium at the St. Louis Hospital, Paris 13 Radium as a Test for Real Diamonds 19 _At the approach of Radium pure gems are thrown into great brilliancy, while imitations remain dull._ M. and Mme. Curie Finishing the Preparation of some Radium 25 M. Alberto Santos-Dumont 29 Severo's Balloon, the "Pax," which on its First Ascent at a Height of about 2,000 feet, Burst and Exploded, Sending to a Terrible Death both M. Severo and his Assistant 33 The Trial of Count Zeppelin's Air-Ship, July 2, 1900 37