Results of Land Observations 



53 



In cases where the observations which make up the mean value are numerous and 

 scattered over the various parts of the day, so that the mean may be practically 

 taken as the mean of day, the local mean times are replaced by the word "various." 

 Occasionally it has appeared desirable, where diurnal variation in declination was 

 observed or where numerous observations were made during a limited interval, to 

 give the local mean times of the beginning and of the end of the series and to 

 indicate the number of determinations from which the mean value is derived by a 

 number inclosed in parentheses: thus 9*".! to ll''.3(7) is to be read "the mean is the 

 result of seven determinations made during the interval Q"".! to 11''. 3, local mean 

 time, inclusive"; 6''.1 to 20^.3 (d. v.) is to be read "eye readings of the suspended 

 magnet were made regularly at short intervals from 6^ A to 20*". 3, local meantime." 

 The local mean times are given according to civil reckoning and are counted from 

 midnight as zero hour continuously through 24 hours; 16'', for example, means 4 

 o'clock p. m. 



The declination values, as also of inclination, are in general given in degrees, 

 minutes, and tenths of minute of arc. For instruments which are not regarded 

 as capable of yielding great accuracy only the nearest minute is given. In some 

 cases the values are inclosed in parentheses, which serve to indicate that the value 

 given is open to question owing to uncertainty of one kind or another. The tabu- 

 lation of values of the horizontal intensity has already been explained above. 



The instruments used are shown in the columns Mag'r (Magnetometer) and 

 Dip Circle. Unless otherwise specified, when two instruments are given in 

 the column of magnetometers, this implies that the first was used for declination 

 observations and the second for horizontal intensity determinations. When the 

 number of an instrument under magnetometer column is italicized, it means that 

 a dip circle has been used in getting the declination by means of the compass 

 attachment and that total instead of horizontal intensity was observed. A desig- 

 nation under the column Dip Circle, e. g., 9.12 stands for "Dip circle No. 9, needles 

 Nos. 1 and 2"; 142.1235, for "Dip circle No. 142, needles Nos. 1, 2, 3, 5"; 9.12(46), 

 for " Dip circle No. 9, needles Nos. 1 and 2 of No. 9 and 4 and 6 of another circle," 

 as explained in the section giving "Dip-circle Corrections." 



In the last column the observer responsible for the observations is indicated by 

 his initials. The observers engaged from time to time in the execution of the 

 work given in this publication were as follows: 



Land Magnetic Observers, 1905-10. 



