HAEMOITIC ANALYSIS AND PREDICTION" OF TIDES. 169 



The period 24 hours should be added or subtracted when necessary 

 in order that the resulting component hours may be between and 23. 



Table 34. For summation of long-period components. — This table 

 is designed to show the assignment of the daily page sums of the 

 hourly heights to the component divisions to which they most nearly 

 correspond. The table is based upon formula (415), The compo- 

 nent division to which each day of series is assigned is given in the left- 

 hand column. For components Mf, MSf, and Aim there will fre- 

 quently occur two consecutive days which are to be assigned to the 

 same component division. In such cases the day which most nearly 

 corresponds to the component division is the only one given in the 

 table, and this is marked by an asterisk (*). The missing day, 

 whether it precedes or follows the one marked by the asterisk, is to 

 be assigned to the same component division. For component Sa a 

 number of conse(?utive days of series are assigned to each component 

 division. In the table there are given the first and last days of 

 each group. 



Table 35. Products -j^-^or Form 444- — This table contains the 



products of the speed of each component as given in Table 3 and the 

 longitude of each of the standard time meridians. These products 

 are for use in formula (492), which gives the value for column A of 

 Form 444. 



Table 36. Angle differences for Form 44^- — This table gives the 

 differences for obtaining and checking the dial settings for February 1 

 and December 31, as entered in Form 445. The differences are de- 

 rived from Tables 16 and 17. 



Table 37. U. S. Coast and Geodetic Survey tide-predicting machine 

 No. 2 — General gears. — This table gives the details of the general 

 gearing from the hand-operating crank to the main vertical component 

 shafts, together with the details of the gearing in the front section 

 or dial case. In this table the gears and shafts are each numbered 

 consecutively for convenience of reference, the gears being designated 

 by the letter G and the shafts by the letter S. In the second column 

 are given the face of each bevel or spur gear and the diameter of each 

 shaft. The next two columns contain the number of teeth and pitch 

 of each bevel and spur gear. The pitch is the number of teeth per 

 inch of diameter of the gear. The worm screw is equivalent to a 

 gear of one tooth, as it requires a complete revolution of the screw 

 to move the engaged wheel one tooth forward. The period of 

 rotation of each shaft and gear is relative and refers to the time as 

 indicated on the face of the machine, which for convenience is called 

 dial time. 



Table 38. U.S. Coast and Geodetic Survey tide-predicting machine 

 No. 2 — Component gears. — This table contains the details of the 

 gearing from the main vertical component shafts to the individual 

 component cranks. Column I gives the number of teeth in the bevel 

 gear on the main vertical component shaft; column II, the number 

 of teeth in the gear on the intermediate shaft that meshes with the 

 gear on the vertical component shaft; column III, the number of 

 teeth in the gear on the intermediate shaft that meshes with the gear 

 on the component crank shaft; and column IV, the number of teeth 

 in the gear on the component crank shaft. 



