b. It should also perform effectively in sea states through 5 

 and under the influence of long-period swells. 



c. It must be capable of measuring over an overall range of 

 7,000 milligals without resetting; this range to cover 977 to 984 

 gals. 



d. Individual readings must be accurate to ±2 milligals over 

 the entire operating range. 



e. It must have a zero or a constant drift rate (not to exceed 



5 milligals) over periods of at least one nnonth, and have automatic 

 input of corrections to readout. 



f. It must be rugged, easy to maintain, and of such size and 

 weight as to permit installation aboard surface ships and submarines. 



g. It must be capable of making automatic corrections for hori- 

 zontal accelerations, and must not be adversely affected by the 

 average horizontal or vertical accelerations of the vessel. 



h. It must eliminate secondary vertical effects. 



i. Its readout must be compatible with Master Shipboard Data 

 Logging and Processing System inputs, where navigational and other 

 related data can be added to gravity data. 



Potential Users and Estimated Number of Units Which They May 

 Require : 



a. U. S. Navy (hydrographic -oceanographic survey and applied 

 research vessels) - 10 to ZO. 



b. U. S. Coast and Geodetic Survey vessels - 2 to 3. 



c. U. S. Air Force (ocean range vessels) - 6 to 8. 



d. Scientific Community - 6 to 15. 



Total: 24 to 46- 



Recommendation Where Instrument Should Be Researched and 

 Developed: 



372 



