CONTENTS. 



I. Memorandum ox the Magnetical Observations made during the Voyage. By Sir Frederick 

 Evans, K.C.B., F.R.S., Hydrographer, ....... 



II. Magnetical Instructions, 1872, ........ 



Addenda to Magnetical Instructions of 1872, ...... 



III. Abstract of Magnetical Observations during the Voyage, . . . . 



Declination or Variation of the Compass. 

 Inclination or Dip. 

 Total Force (British Units). 

 IV Abstract of Magnetical Observations made at Land Stations, prefaced with Descriptive 

 References to the Positions (Observation Spots) of the Instruments, . 

 Declination or Variation of Compass by Declinometer and Compasses. 

 Inclination or Dip. 



Absolute Horizontal Force (British Units). 

 V. Abstract of Variations of the Compass observed at Sea, . . . . . 



VI. Abstract of Observations with Fox Circles, ...... 



Inclination or Dip. 

 Total Force (British Units). 

 Tables of Corrections for Observations made at Sea — 



1. Declination. Coefficients of Standard and Fox Compasses, 



Computed Deviations of Standard Compass, 



Computed Deviations of Compass in Fox Circle position, 



2. Inclination. Correction for direction of Ship's head, . 



3. „ Correction of 1ST. for values of 



R 



AH' 



4. 



Correction — for values of d, 



5. Total Force. Tables of Equivalent Weights, . 



6. „ Correction for direction of Ship's head, . 



7. Abstract of constants of the Ship's Magnetic Force, 



VII. Memorandum on the Meteorological Observations made during 

 Commander Tizard, R.N., . 

 VIII. Abstract of Meteorological Observations, . 



the Voyage. By Stafl- 



1 



8 



21 



23 



45 



74 

 100 



274 

 27G 

 278 

 2S0 



282 



290 



291 

 296 

 298 



300 

 305 



Appendix A. — The Pressure Errors of the Challenger Thermometers. 

 By Professor P. G. Tait, M.A., Sec. R.S.E., Professor of Natural Philosophy in the University of Edinburgh. 



Received 1st July 1881. 



Appendix B. — On the Petrology of St. Paul's Rocks (Atlantic). 



By Professor A. Renard, F.G.S. 



Received 30th October 1879. 



