vi. CONTENTS. 



PAGE. 



M. LEMSTROM : On the Aurora Borealis ." .. .. '.+ 158 



Mr. DE LA RUE, D.C.L., F.R.S.: Astronomical Photography 164 



Professor BLASERNA, of Rome : On the Variable State of Electric Currents .. .. 173 



Mr. BROOKE, M.A., F.R.S. : Magnetic Registration 177 



Professor RIJKE : On the Historical Instruments from Leyden 184 



Baron FERDINAND DE WRANGELL : On a New Form of Voltameter 189 



Rev. ROBERT MAIN, M.A., F.R.S. : On a Newtoniaa Reflecting Telescope of Sir 



W. Herschell 191 



Professor DE ECCHER : Continuation of Remarks on the Italian Exhibits .. .. 195 



The PRESIDENT : Closing Remarks .. ... - 201 



SECTION MECHANICS (including Pure and Applied 

 Mathematics and Mechanical Drawing). 



The President, Mr. C. W. SIEMENS, D.C.L., F.R.S.: Opening Address .. 204 



Sir JOSEPH WHITWORTH, Bart., D.C.L., F.R.S. : On Linear Measurement .. .. 216 



M. TRESCA 221 



Mr. CHISHOLM 222 



Sir JOSEPH WHITWORTH, Bart., D.C.L., F.R.S. : In Reply 226 



Mr. C. W. MERRIFIELD, F.R.S. : On Solid Measurement 227 



Professor Sir WM. THOMSON, LL.D., F.R.S. : Electrical Measurement .. .. 230 



The PRESIDENT 251 



M. TRESCA: On the Fluidity and Flow of Solid Bodies .. .. 252 



M. TRESCA : The above Paper in the Original French .. .. ,. .. .. 25 



The PRESIDENT 26 



Mr. J. SCOTT-RUSSELL, F.R.S 2 



The PRESIDENT: Remarks as to Explanation of Objects in Exhibition at Stated 



Intervals . . 269 



Professor ALEX. B. W. KENNEDY : On the Collection of Kinematic Models by 



Professor Reuleaux, of Berlin 269 



Mr. BARNABY : On Naval Architecture . . 284 



The PRESIDENT .. 298 



Mr. FROUDE, M.A., F.R.S. : On Experiments in Relation to Naval Architecture .. 298 



Mr. THOMAS STEVENSON : On Lighthouse Apparatus 315 



General MORI N: Isotes on Warming and Ventilation .. .. 329 



Messrs. E. DENT & Co. : On Time Measurers 336 



Mr. GLASGOW 344 



F. J. BRAMWELL, M. Inst. C.E., F.R.S. : On Prime-Movers 348 



The PRESIDENT 380 



Mr. HACKNEY : On Furnaces 381 



Mr. PREECE : Electric Telegraphs 4 6 



The PRESIDENT : Closing Remarks 4*9 



