lOfiK 
THE VOYAGE OF H.M.S. CHALLENGER. 
1 >r Gerhard Schott’s observations on currents, temperature, and specific gravity of sea- 
water. on a sailing voyage to China, show how important additions to oceanographical 
knowledge can he made on such a voyage. 1 
Th- great advances in the Science of Oceanography during recent years, through the 
researches and expeditions indicated above, will be evident to all who may compare the 
knowledge possessed thirty years ago with what is now known concerning the depth of 
;: c ocean. - represented on the bathymetrical charts which accompany these volumes, 
with the data in regard to the temperature and specific gravity of the ocean at dif- 
f, ;, nt depths as exhibited on the maps in Dr. Buchan’s Report on Oceanic Circulation, 
or with the information on the biology of the Great Ocean Basins contained in 
the following pages. 
1 Petermann’y Mitteil., Erganzungshett No. 109, 1S93. 
Hooke’s Sounding Machine and Water-bottle (see pp. 57 and 66). 
