124 U. S, COAST AISTD GEODETIC SURVEY. 



The angular motions of the individual components, as indicated by 

 the quantity at in formulas (472) and (473), are represented in the 

 machine by the rotation of short horizontal shafts having their bear- 

 ings in the parallel plates of the component frames. All of these 

 component shafts are connected by a system of gearing with the hand 

 crank at the left of the dial case and also with the time-registering 

 dials, so that when the machine is in operation the motion of each of 

 these shafts will be proportional to the speed a of the corresponding 

 component, and for any interval of time or increment in t as indicated 

 by the time dials the amount of angular motion in any component 

 shaft will be equal the increment in the product at corresponding 

 to that component. 



Since the corresponding angles in formulas (472) and (473) are 

 identical for all values of t, the motion provided by the gearing will be 

 applicable alike to the solution of both the formulas. The mechanism 

 for the summation of the terms of formula (472) is situated on the side 

 of the machine at the left of the operator, and for convenience this 

 side of the machine is called the "height side" (fig. 12), and the mech- 

 anism for the summation of the terms of formula (473) is on the right- 

 hand side of the machine, which is designated as the "time side" 

 (fig. 13). 



In Table 37 are given the details of the general gearing from the 

 hand-operating crank to the main vertical component shafts, together 

 with the details of all the gearing in the front section or dial case. 



It will be noted that S-6 (fig. 16) is the main vertical shaft of the 

 dial case and is connected through the releasable gears to the hour 

 hand, the minute hand, and the day dial, respectively. The releas- 

 able gears permit the adjustment of these indicators to any time 

 desired. After an original adjustment is made so that the hour and 

 minute hand will each read at the same instant that the day dial 

 indicates the beginning of a day, further adjustment will, in general, 

 be unnecessary, as the gearing itself will cause the indicators to main- 

 tain a consistent relation throughout the year, and by use of the hand- 

 operating crank the entire system may be made to indicate any time 

 desired. The period of the hour-hand shaft is 24 dial hours, and the 

 hand moves over a dial graduated accordingly {3, fig. 12). The 

 minute-hand shaft, with a period of 1 dial hour, moves over a dial 

 graduated into 60 minutes (^, fig. 12). 



The day dial, which is about 10 inches in diameter, is graduated into 

 366 parts to represent the 366 days in a leap year. The names of the 

 months and numerals to indicate every fifth day of each month are 

 inscribed on the face of the dial. This dial is located just back of the 

 front plate or face of the machine, in which there is an arc-shaped open- 

 ing through which the graduations representing nearly two months 

 are visible at any one time (4, fig- 12) . The progress of the days as the 

 machine is operated is indicated by the rotation of this dial past an 

 index or pointer just below the opening {6, fig. 12). This pointer is 

 secured to a short shaft which carries at its inner end a lever arm with 

 a pin reaching under the lower edge of the day dial, against which it is 

 pressed by a light spring. A portion of the edge of the dial equal to 

 the angular distance from January 1 to February 28 is of a slightly 

 larger radius, so that the pin pressing against it rises and throws the 

 day pointer to the right one day when this portion has passed by. On 

 the last day of December this pointer will move back one day to its 

 original position. 



