CONTENTS. 



Page 

 I. The Invariants of Linear Differential Expressions. By F. Irwin 1 



II. The Damping of the Oscillations of Swinging Bodies by the Resisl- 



anceoftheAir. By B. O. Peirce 61 



III. Note Concerning the Silver Coulometer. By T. W. Richards . 89 



IV. A rtificial Lines for Continuous Currents in the Steady State. By 



A. E. Kennelly • 95 



V. The Effect of Alkaloids on the Early Development of Toxopneustes 



Variegatus. By Sergius Morgulis 131 



VI. The Preface of Vitruvius. By M. H. Morgan 147 



VII. A Revision of the Atomic Weight of Arsenic. — The Analysis of 



Silver Arsenate. By G. P. Baxter and F. B. Coffin . . 177 



VIII. The Measurement of High Hydrostatic Pressure. (I.) A Simple 



Primary Gauge. By P. W. Bridgman . . " 199 



IX. The Measurement of High Hydrostatic Pressure. (II.) A Secondary 



Mercury Resistance Gauge. By P. W. Bridgman .... 219 



X. An Experimental Determination of Certain Compressibilities. By 



P. W. Bridgman 253 



XI. The Theory of Ballistic Galvanometers of Long Period. By 



B. O. Peirce 281 



