The Survey of the Coast. 73 



attached to the Survey, whereby he can anchor the ship in mid- 

 ocean and observe the direction and velocity of the current as 

 from a stationary body, and with a " current meter," also his own 

 invention, determine the same factors hundreds of feet below the 

 surface ; thus ascertaining not only the movement at the surface, 

 but the depth of the body of water that moves, and the velocity 

 at various depths, so that finally we have the volume — a quantity — 

 to be followed until it meets other currents or is absorbed in the 

 vast expanse. Already current observations have been recorded 

 with the ship anchored at the great depth of eighteen hundred 

 fathoms ; and arrangements have been perfected that it is be- 

 lieved will prove successful at the greater depth of three thousand 

 fathoms. It is impossible with our superficial knowledge of the 

 great ocean currents to estimate the benefits that will be derived 

 from their systematic exploration. It is not probable that the 

 absolute determination of their limits would produce such a revo- 

 lution in navigation, as was caused by Maury's wind charts, but 

 it is reasonably certain they would prove a valuable assistance to 

 the navigator, and in the great channels and bays of the world 

 increase his facilities for the successful navigation of his ship. 

 Not a little of their value, perhai)s the larger part, will be of an 

 indirect nature, resulting from their study by investigators in the 

 natural sciences interested in utilizing the bounties of nature for 

 benefit of man. 



The Survey was instituted for the determination of facts, and 

 the presentation of them in an intelligible form. It does not pro- 

 mulgate theories, and has no use for them beyond the assistance 

 they may be in indicating the line of reseai'ch necessary to ascer- 

 tain the facts ; but rather leaves to the student the formulation 

 of the theories that may be deduced from the facts presented. 

 The publications of the Survey are, therefore, calculated to con- 

 tain only useful, practical information, on the subjects of which 

 they treat. An examination of them will show this to be the 

 case, and further, that error has more likely been committed by 

 over-caution, than a too free use of the material at command. 

 Doubtless much has been suppressed through lack of means, as it 

 has always been the aim of the Superintendents to expend the 

 appropriations in producing the most useful results, whether in 

 surveys to be made or facts to be published. It necessarily 

 requires many years to complete- a precise survey over a large 

 area ; and in the work of the Coast Survey, with the people in 



