x THE VOYAGE OF H.M.S. CHALLENGER. 



for magnetical and other physical inquiries. From the hypsometrical 

 data tinted on the maps, the influence of height on the distribution of 

 pressure, temperature, and other meteorological phenomena may be noted, 

 this influence being more particularly observed in those parts of the world 

 whence observations from numerous stations are available. The revision 

 of these isothermal and isobaric lines of the globe form a striking feature 

 of the Report, and will be welcomed by all meteorologists. Mr. Buchan 

 is in every way to be congratulated on the completion of this classic work, 

 which must for many years to come be a standard book of reference. 



Part VI. — In volume II. of the Narrative of the Cruise of H.M.S. 

 Challenger, published in 1882, there is a detailed Statement of all the 

 Magnetic Observations made in various parts of the world during the 

 Expedition. These Observations, after having been reduced by the officers 

 of the ship, were prepared for publication by Staff- Commander Creak, 

 R.N., F.R.S., of the Hydrographic Department of the Admiralty. 



A full discussion of the Challenger Observations, and their bearing on 

 the existing state of our knowledge of Terrestrial Magnetism, not having 

 been included in the above-mentioned Report, this Paper has been prepared, 

 at my request, by Commander Creak. 



Commander Creak had ascertained the Magnetic character of the ship 

 previous to her departure from England in 1872, and since then all the 

 information which has reached the Admiralty has passed through his hands. 



Captain Wharton, R.N., F.R.S., the Hydrographer, having placed the 

 whole of the data in the Hydrographic Office at his disposal, Commander 

 Creak has been able to prepare a most valuable Report. 



The accompanying Charts may be said to contain in graphic form the 

 results of all the available existing observations of the three elements of 

 Terrestrial Magnetism up to the year 1888, local magnetic disturbance in 

 particular areas on land excluded. 



The Report extends to 18 pages of letterpress, with 4 large charts 

 and 2 plates. 



Part VII. — This Report on the Rock Specimens collected in certain 



