First published in 1936, this volume contains six of the Halley Stewart Lectures - originally founded "For Research towards the Christian Ideal in All Social Life" - by some of the greatest of English scientists of the mid-20th century, each a leading authority in his respective field: cosmology, physics, meteorology, medicine and genetics. The final lecture considers the relationship between scientific knowledge and human ideals, commenting on the paradox that a century which produced such scientific advance also witnessed the most concentrated period of social, economic and political turmoil in world history.

First published in 1936, this volume contains six of the Halley Stewart Lectures - originally founded "For Research towards the Christian Ideal in All Social Life" - by some of the greatest of English scientists of the mid-20th century, each a leading authority in his respective field: cosmology, physics, meteorology, medicine and genetics. The final lecture considers the relationship between scientific knowledge and human ideals, commenting on the paradox that a century which produced such scientific advance also witnessed the most concentrated period of social, economic and political turmoil in world history.

These documents do nothing less than bear witness to one of the most dramatic changes in the foundations of science. The book has three sections that cover general relativity, epistemological issues, and quantum mechanics. This fascinating work will be a vital text for historians and philosophers of physics, as well as researchers in related physical theories.

Reprint of the original, first published in 1921.

This is an EXACT reproduction of a book published before 1923. This IS NOT an OCR'd book with strange characters, introduced typographical errors, and jumbled words. This book may have occasional imperfections such as missing or blurred pages, poor pictures, errant marks, etc. that were either part of the original artifact, or were introduced by the scanning process. We believe this work is culturally important, and despite the imperfections, have elected to bring it back into print as part of our continuing commitment to the preservation of printed works worldwide. We appreciate your understanding of the imperfections in the preservation process, and hope you enjoy this valuable book.

This is a reproduction of a book published before 1923. This book may have occasional imperfections such as missing or blurred pages, poor pictures, errant marks, etc. that were either part of the original artifact, or were introduced by the scanning process. We believe this work is culturally important, and despite the imperfections, have elected to bring it back into print as part of our continuing commitment to the preservation of printed works worldwide. We appreciate your understanding of the imperfections in the preservation process, and hope you enjoy this valuable book.

Text extracted from opening pages of book: CONCERNING THE NATURE OF THINGS Six Lectures delivered at the Royal Institution By SIR WILLIAM BRAGG K. B. E., D. Sc., F. R. S LONDON G. BELL AND SONS LTD. * 19* 5 RO IN GRFAF BKITAIN BY KD CLAY & SONS, LIMIJED, BUNC. AY, SUFFOLK. PREFACE IT was my endeavour at the Christmas Lectures given at the Royal Institution in 1923-24 to describe certain features of the recent discoveries in physical science. Many of the facts that have come to light might well be the subject of Lectures adapted to a Juvenile Auditory/' and would be at the same time interesting and helpful; interesting because they display a beautiful order in the fundamental arrangement of Nature, and helpful because they have given us light on many old questions, and will surely help us with many that are new. I was aware of two special diffi culties. The first was the difficulty of under standing the minuteness of the scale on which the action and properties of the atoms must be repre sented; but, after all, this was only a difficulty due to unfamiliarity, and would come to a timely end. The other was the difficulty of grasping arrangements in space. There are some who think that this difficulty is incurable, and that it is due to the want of some special capacity, which only a few possess. I am persuaded that this is not the vi PREFACE case: we should have nearly as much difficulty in grasping events in two dimensions as in three were it not that we can so easily illustrate our two dimensional thoughts by pencil and paper. If one can turn over a model in one's hand, an idea can be seized in a mere fraction of the time that is required to read about it, and a still smaller fraction ofthe time that is required to prepare the description. Perhaps some of the readers of this book will be sufficiently interested to make models of the few crystal structures that are mentioned in it, and may even go on to other structures that are described in larger books or in original papers. I have added somewhat to the lectures as originally given. The additions are intended to make the treatment of the subject a little more complete: they were not very suitable for con sideration at the lectures, but are perhaps per missible in the book because the reader can omit them if he desires or read them more than once, or consider them with a model in his hand. At the end of the book there is a short note on the making of models. CONTENTS LECTURE I I'AGK THE ATOMS OF WHICH THINGS ARE MADE . . i LECTURE II THE NATURE OF GASES ..... 42 LECTURE III THE NATURE OF LIQUIDS ..... 83 LECTURE IV THE NATURE OF CRYSTALS: DIAMOND . .116 LECTURE V THE NATURE OF CRYSTALS: ICE AND SNOW . 160 LECTURE VI THE NATURE OF CRYSTALS: METALS . . . 200 LIST OF PLATES PI ATE To face page I. ( A) MODEL OF BISMUTH CRYSTAL. (&) THE SHAKING SAND BOX . . .17 II. SHIMIZU-WILSON RAY TRACK APPARATUS . 26 III. ALPHA RA. Y TRACKS .... 28 IV. ( A) BAR MAGNETS ON SPIRAL SPRINGS. ( B) MODELS OF ATOMS WITH ELECTRONS . 32 V. ( A) FLOATING MAGNETS. ( B) CRYSTALS IN TUBE CONTAINING EMANATION . . 38 VI. ( A) TUNING FORK OVER JAR. ( B) FOG APPA RATUS ...... 56 VII. CIGARETTE SMOKE ..... (> o VIII. EXPERIMENT SHOWING THE PRESSURE OF THE ATMOSPHERE .... 65 IX. CAVITATION CAUSING EROSION OF PROPELLER BLADES ..... 91 X. ( A) LARGE DROP OF ORTHOTOLUIDINE. ( B) ONE SOAP BUBBLE INSIDE ANOTHER . 95 XI. ( A) CIRCLES CLEARED BY MINUTE DROPS OFOIL. ( B) THE CAMPHOR BOAT . . 104 ix t LIST OF PLATES PLATE-To face page XII. ( A) STORMY WATER. ( fi) OIL STILLING THE STORM, ( c) GRAPE IN SODA WATER . 106 XIII. CRYSTALLINE FORMS .... 124 XIV. ( A) DIAMOND MODEL. ( B) PLANE LATTICE IN THE DESIGN OF A WALL-PAPER . 135 XV. THE CULLINAN DIAMOND . . - 145 XVI. ( A) LAYERS OF THE GRAPHITE CRYSTAL. ( B) POSSIBLE FORMS OF THE BENZENE RING 146 XVII. SNOW CRYSTALS OF VARIOUS FORMS . . l6o xviii. MORF: SNOW CRYSTALS . . . .161 XIX. A HALO AND MOCK SUNS. . . . 163 XX. ( A) GLACIER ICE. ( B) MODELS OF ICE STRUCTURE

Immanuel Kant's Critique of Pure Reason is widely taken to be the starting point of the modern period of mathematics while David Hilbert was the last great mainstream mathematician to pursue important nineteenth century ideas. This two-volume work provides an overview of this important era of mathematical research through a carefully chosen selection of articles. They provide an insight into the foundations of each of the main branches of mathematics - algebra, geometry, number theory, analysis, logic, and set theory - with narratives to show how they are linked.
Classic works by Bolzano, Riemann, Hamilton, Dedekind, and Poincare are reproduced in reliable translations and many selections from writers such as Gauss, Cantor, Kronecker, and Zermelo are here translated for the first time. The collection is an invaluable source for anyone wishing to gain an understanding of the foundation of modern mathematics.

Immanuel Kant's Critique of Pure Reason is widely taken to be the starting point of the modern period of mathematics while David Hilbert was the last great mainstream mathematician to pursue importatn nineteenth century ideas. This two-volume work provides an overview of this important era of mathematical research through a carefully chosen selection of articles. They provide an insight into the foundations of each of the main branches of mathematics - algebra, geometry, number theory, analysis, logic, and set theory - with narratives to show how they are linked.
Classic works by Bolzano, Riemann, Hamilton, Dedekind, and Poincare are reproduced in reliable translations and many selections from writers such as Gauss, Cantor, Kronecher, and Zermelo are here translated for the first time. The collection is an invaluable source for anyone wishing to gain an understanding of the foundation of modern mathematics.