.PEOVISIONAL PREFACE. 



On the return of the exploring voyage of H.M.S. Challenger in the summer 

 of the year 1876, I was instructed by Her Majesty's Government, in 

 pursuance of the arrangement undei* which I had undertaken the direction 

 of the Civilian Scientific Staff on board, to prepare a detailed Report on 

 the scientific results of the expedition. 



A complete report of a voyage such as that of the Challenger must consist 

 of two parts, which, although interdependent, are essentially distinct. The 

 first of these includes the account of the whole mass of hydrographical details, 

 and the magnetidal, meteorological, and other physical observations which 

 enter more or less fully into the routiae of every surveying ship ; "with the 

 exception of the determination of the specific gravity of sea-water, which 

 was undertaken by Mr J. Y. Buchanan, M.A.., F.R.S.E., the whole of the 

 work under this head was carried on on board the Challenger by the Naval 

 Surveying Staff, and it was conducted with more than ordinary care and skill. 

 A copy of the observations was taken daily during the voyage for the use of 

 the civilians. 



The second part consists of the record of the observations of the natural- 

 ists, the descriptions of the animal forms acquired which are new to science, 

 the report of the special work of the geologist &.nd of the analytical chemist, 



