New Britain herald., 1928-10-12
FUTURE. BENEFITS
 IN NAVAL VOYAGE
hpsddn Of S-li Along Coast
 k Important

Washington. Oct. 11.-R-How science looks far into the future while pursuing little abstract details of nature's inconcelvably complicat- ed mechanism Is illustrated by the two-months' cruise undertaken by the naval submarine S-21 along the Atlantic coast and into the Gulf of Mexico and the Caribbean sea.
 The immediate objective of the trip is to enable I group of sci- entists to measure variations in the force of gravity along the American continental shelf and other waters in which the submarine will oper- ate. including the mysterious areas of great depth known as Mares Deep. near Porte Rico. Bartlett Deep. south of Cuba, and Sigsbee Deep. in the gulf.
 Ultimately these gravity deter- minattons, varying with differences in altitude and longitude and in the density and stresses in the earth's crust, are expected to be made over practically it's entire surface. When that is accomplished science will be closer to an exact knowledge of the figure of the earth and of the compo- sition and condition of its crust. which is assumed by geodesists to extend 75 or so miles inward to the relatively more stable core.
 With this and related informa- tion it will then have. in the words of naval observatory expert. "a more accurate yardstick' to measure the distance to the sun and stars, a means perhaps of predicting earth quakes with some assurance. an agency for tracing valuable mineral deposits under water and data upon which new discoveries valuable to human welfare may be revealed"
 The scientific work of the expe- dition is being done by Dr. F. A.. vening Meinesz of Holland. an au- thority on gravity determination at sea; Dr. Fred E. Wright. geo. physicist of the Carnegie Institution of Washington. which after consul tation with the navy department in- vited the Dutch scientist to America, and Elmer B. Collins of the navy's hydrographic office.
 IL is being accomplished with ap- paratus developed by Dr. Meinesz. This masdve Dutchman. 6 l-2 feet tall. already has made 8 number of Txhsnryo %{aro {n ~,h,r, o ri ac s.r< o,,< by his own government between the Netherlands and the Dutch East Indies and, on one voyage which consumed 19s days, from Holland through the Panama canal to Sumatra.
 His instrument is designed to overcome the difficulty which has made 1t impossible even in subma- rines to make gravity determina- tions at sea with the apparatus used on land. Instead of a single pendu- lum. the swings of which are timed to ten-millionth of . second, he uses three hung from little bars, or knife edges" in such way that the effect on each of the slight rolling motion of q submarine 60 to 100 feet under the surface of the sea will be offset by its effect on the others.
 The record of each observation is obtained by the use of mirrors on the tops of the pendulums, which re- fleet beams of light through prisms into the lens of camera. At the same time variations in the tempera- . ture of the pendulum chamber are similarly recorded, and the precise measurement of the time of the swings. which speed up with increase ip sravity and slow down with it's decline, is controlled by carefully adjusted chonometers electrically operating little shutters to cut off the light at fixed intervals.
 These chronometers are checked against the rythmic time signala broadcast from the naval observa- tory here through the Annapolis radiostation. and the depth and con- tour of the ocean bed beneath the points of gravity observation ia measured with sonic depth re. corder. The pendulum apparatus is of such small dimensions about secen cubic feet-that it can be oper. ated successfully in the control room