230 KNOTT AND TANAKADATE 



The instrument for measuring altitudes is a brass quadrant, 19 

 inches in radius, with a telescope fixed to one of the straight limbs. 

 The whole is mounted on an upright, wooden piHar resting on three 

 legs. The telescope and quadrant, Avhich move together in a vertical 

 plane about a pivot passing approximately through the centre of gra- 

 vity, can be clamped in any required position. From the angle of 

 the quadrant a " plummet-line," in the form of a brass rod, hangs. 

 The position of this rod, as it hangs just free of the quadrant arc, 

 indicates the angle to be read. The quadrant is graduated in a manner 

 very similar to the azimuth circle, only to a finer degree of division. 

 The radial lines measure to thirds of a degree ; and by means of the 

 " diao'onal-scale " arransfement, an2:les mioht be read to half-minutes. 

 On the azimuth circle again it would be difiicuh if not impossible to 

 read to minutes even. 



With such instruments did [no carry out his survev. Abcnit 

 1135 direct measurements of latitudes were taken bv means of the 

 quadrant. The distances between successive stations were measured 

 by three distinct methods. Ropes were used as onr land surveyors 

 use chains ; also a kind of wheel or roller, the number of rev(^lntions 

 of which measured the distance travelled. Then with the azimuth 

 instrument in combinaticjn with the compass a triangulation by means 

 of prominent hills and land-marks was carried out. From the dis- 

 tances so obtained, the louo-itudes seem to have been calculated. 



The results of Ino's labours are given in the " Dai Nippon En- 

 kai-jis-soku-roku," or, the Record of the True Survey of the Coasts 

 of Japan (1821, 14 volumes). Tliis treatise existed simply in 

 manuscript till 1870 (Meiji, 8), when it was pul)lished in proper 

 book form by the Tokyo University ( Hitotsu-bashi ) — at that time 

 known as the Daigaku Nankö. Three kinds of maps were constructed, 

 the largest consisting of 30 different sheets, the medium sized of two, 



