4-iO Miscellaneous Intelligence. 



tude work was charged with researches in gravity, magnetism, 

 meteorology, etc. One of the theories proposed to explain the 

 changes of latitude was that of transfers of large masses of molten 

 matter in the earth's interior. In order to test this it was decided 

 to measure the force of gravity every night that latitude observa- 

 tions are made, and this is now being done at Waikiki with an 

 accuracy capable of detecting changes no greater than the one 

 hundred thousandth part of the quantity measured. Practically 

 stated we may say that a body falling toward the earth passes 

 over about sixteen feet in one second ; if from some unknown 

 cause the force of gravity should change so as to increase this 

 distance by only one-five hundredth of an inch, this slight increase 

 would be easily detected by the methods employed. 



To arrive at these results it is necessary to have a very accurate 

 means of measuring time. This is done by referring all compari- 

 sons to the movement of the stars whose passages across the 

 meridian are registered electrically on a revolving cylinder. A 

 button is pressed when the star crosses a spider-thread stretched 

 vertically through the field of the telescope, and instantly the fact 

 is registered on the chronograph. The exact moment of transit 

 can easily be known to within one-hundredth of a second. Dur- 

 ing the entire evening a pendulum is allowed to oscillate under 

 the influence of the force of gravity. Means are used by which 

 the duration of one vibration may be known with no greater 

 error than a few millionths of a second. The gravity investiga- 

 tions are made for the sake of discovering whether there is any 

 change in the force from day to day, and not for the purpose of 

 knowing what the actual force is; in other words, the question is 

 not how far a body will fall in a second, but whether it falls 

 faster at one time than at another. 



The methods followed are similar to those employed on Halea- 

 kala in 1887, which gave such conclusive evidence in regard to 

 the formation of Maui, and which bore out Prof. Dana's geologi- 

 cal theories. The same operations will be conducted next sum- 

 mer on Mauna Kea, and will throw light on its density and inter- 

 nal structure. This way of weighing the mountains has been 

 employed many times in recent years. During the last cruise of 

 the U. S. S. Pensacola to Africa, investigations were made on 

 many of the islands of the Atlantic, which gave the interesting 

 result that they are all comparatively light. The same instru- 

 ments that were used in the African work were employed in these 

 islands in 1887 and were sent to the South Seas with the TJ. S. 

 Solar Eclipse Expedition in 1883, so that a fair portion of the 

 earth's surface has been studied by the same method, which adds 

 much to the strength of the result. 



The present operations will close this fall, but the complete dis- 

 cussion of the observations will require probably a year more, so 

 that the definitive results will not be known before the latter part 

 of 1893. 



