HARMONIC ANALYSIS AND PREDICTION OF TIDES 9 
tent upon the labor involved since their rejection would not seriously 
affect the final results. 
29. The formulas for the moon’s true longitude and parallax on 
pages 19-20 are said to be given to the second order of approximation, 
a fraction of the first order being considered as one having an approxi- 
mate value of 1/20 or 0.05, a fraction of the second order having an 
approximate value of (0.05)? or 0.0025, a fraction of third order having 
an approximate value of (0.05)* or 0.000125, etc. As these formulas 
provide important factors in the development of the equations repre- 
senting the tide-producing forces, they determine to a large extent 
the degrees of precision to be expected in the results. 
