ACTIVE TYPE OF STABILIZING GYRO. 215 



from these or any other motions which do not represent the proper roll 

 component. Two views of this apparatus are shown in Fig. 16, Plate 89, 

 and Fig. 17, Plate 90. 



Figure 18, Plate 91, and Fig. 19, Plate 92, show in plan and also in eleva- 

 tion similar gyroscopic recording apparatus for the U. S. Navy, upon which 

 six records are made on a single tape. These are as follows: — Curves 

 indicating both roll and pitch, means for spotting either, the base line, 

 timing and means for drawing a curve indicating the simultaneous azimuth 

 of the ship's heading relative to any desired fixed line, as the meridian, the 

 running of the sea, direction of wind, etc., etc. 



Universal or compound angular motion may be said to be made up of 

 three primary components similar to the three primary components of 

 white light and probably from the same basal cause; thus universal angular 

 motion may be resolved into motion about three axes, all normal to each 

 other and bearing the relation of the three converging margins of a cube. 

 Gyroscopes mounted for producing motion records, so far as has been hereto- 

 fore published, are in each case critical to all of the three above named 

 components. In this manner the rolling record is liable to be falsified by 

 motions which really have their origin in yawing, or pitching, or both. 

 Suffice it to say that a mounting has been finally adopted by means of which 

 any two of the three components are entirely eliminated and prevented from 

 influencing the records, which are thus confined to any single component 

 of motion that may be desired. At the same time the natural period of 

 the apparatus is made so long as to be entirely removed from any influences 

 of the comparatively short periods of motion to the ship itself. In this 

 manner, a base Une of extreme rigidity has been created about which all 

 of the ship's motions take place and which is sensitive and critical to only 

 one selective component of such motions, it having been found possible to 

 record the most minute motions of the ship in this selected plane. For 

 instance, upon one occasion distinct record was made on the Worden, when 

 her displacement was about 700 tons, of two men walking from one beam to 

 the other, indicating about four minutes of arc upon the record. 



Through the important work to which only brief reference has here 

 been possible, knowledge of the performance of the stabilizing gyro under 

 service conditions has been accumulated. This is now such as to enable 

 us to calculate with all necessary accuracy the weight and space occupied 

 in connection with practically any plant, either stabilizing or ice-breaking; 

 also to predict with certainty what the result will be, the amount of power 

 required and also to prescribe with fair degree of accuracy about what will 

 be the stabilizing or rolling factor upon any given ship with the new active 

 gyros fitted. 



