^[A(tXETIC SURV1'^,V of JAPAN'. 17."» 



ol).sor\'nti<iii of the :i/iiiiiiili of I'nhii'is, n few .socoikIs" ci-nic in ilic 

 (leterminntioii of the clock-ei-roi- wns insisriiifiranf. ( »of-asioiiiillv, 

 however, cloudy wenrlior prevented the observation of Polnris, nnd 

 in that ease the Siin'> nzininth wns t;iken instead. Ft was customary 

 indeed, if the stntic^n were reached early enoui^h in tlie afternoon, to 

 take a Sun's azimuth, in case tlie night should n«^t prove propitious : 

 and in not a few cases the declination was obtained bv both methods. 

 ()nc(> or twice, on broken nights, Jupiter, Arcturus, or Spica was 

 utilised for ol)taining the true astronomical meridian. 



The azimuth was taken in the usual Avay by means of the small 

 mirror fitted to tlie Kew instrument. If Polaris or other star were 

 being observed, foui- transits were taken, — first, two with the stat- 

 in front of the observer, the mirror being reversed on its Y's between 

 the observations, and then two similarly with the star behind. Ff the 

 sun were being observed, two transits Avere taken, one foi'e and one 

 back, the mirror being in each case reversed between the contacts. 

 In this way the small errors of adjustment were tak<'n projxr account 

 of. 



[mmediately before or immediately after the transit observations, 

 the magnetic declination was taken, the magnet being always viewed 

 in the inverted as well as in the pi-oper position. During the whoh- 

 survey, the point on the scale corresponding to the magnetic axi< 

 never varied by as much as the tenth of :i small division. 



On two occasions onlv did continued wet weather jirevenf th(> 

 azimuth obser\atioii l)eing made — namely at fchijioseki (N"o. 7) and 

 at Ueda (No. 87) 



In the final workini:' up oi' the i-esults onlv those stations .-ire 

 chosen ;it which the azimuth was obtained by means of Poliu-is 

 observations. Ii> nil except one case, these Polaris ob^ccvations wej-e 

 madebetweenthehonrsofSp.nl. and 12 p.m. locnl time: in thai 



