DECIMAL CLASSIFICATION 
525.6 Tides 
61 Mathematic theory 
.62 Effect of sun and moon in producing tides 
.63 Distribution, diurnal inequality, spring and neap, priming 
and lagging 
Establishment of a port Coast form modification 
Velocity of hight of tide wave 
Tides on inland seas 
Supposed effect in retarding Earth's revolution 
Tide registering and predicting machines 
Tide tables 
Twilight 
Geodesy 
526.2-.8 apply to surveys of large tracts, requiring allowance for earth’s curva- 
ture and more exact methods of determination. For local surveys see 526.9 
Theory and determination of Earth’s figure 
Potentials of ellipsoids 
Equilibrium of rotating spheroid 
Law of ellipticity 
Airy’s and Pratt’s theories as to attraction of mountains 
Determination of figure by Airy, by Bessel, and by Clarke 
Ellipsoidal figure and position of axes 
Geoidal figure 
Base mesuring and apparatus 
Standards of length and temperature 
Apparatus of Struve, Bessel, Colby, U. S. coast survey, 
U. S. lake survey, etc. 
Adjustments of apparatus 
Location of base line 
Field operations 
Calculation of results and corrections 
Verification 
Field work of triangulation 
Reconnaissance 
Stations 
Names, signals, tripods, scaffolds and towers, surface and underground monu- 
ments 
Observations, instruments and records 
Reduction to station’s center 
Corrections for phase of signal and eccentricity 
Spirit leveling 
Barometric leveling | he are mols. e553 
Triconometric leveling 
64 
.65 
.66 
.67 
68 
.69 
7 
526 
ir 
33 
34 
35 
36 
37 
38 
20