238 NATURAL SCIENCE. April, 1896. 



screws be turned through any angle, the magnitude and direction of 

 the tilt given to the.stand can be easily determined. The first screw 

 tilts the axis of rotation in the plane of the pendulum, and its object 

 is, therefore, to regulate the sensitiveness of the instrument. If either 

 of the other two screws is turned through a known amount, the angle 

 through which the axis of rotation is tilted in a perpendicular 

 direction is ascertainable, and the corresponding deflection of the 

 point of light on the scale or photographic paper can be measured. 



REFERENCES. 



1. Barrett and Brown. — " Practical Physics," p. 241 ; 1892. 



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pp. 61-63 ; 1894. 



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1893 (bifilar pendulum, pp. 291-299; horizontal pendulum, pp. 303-308) ; 

 1894. 



5. . — " Bifilar Pendulum for Measuring Earth-Tilts." Nature, 



vol. 1., pp. 246-249 ; 1894. 



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5. Milne, J. — " Reports of the Committee on the Earthquake and Volcanic 



Phenomena of Japan." Brit. Assoc. Rep., 1892 (horizontal pendulum, 

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vol. iii., pp. 55-60 ; 1894. 



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mesurables les variations occasionnees dans 1'intensite et la direction de la 

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11. Rebeur-Paschwitz, E. von — "Das Horizontalpendel und seine Anwen- 



dung zur Beobachtung der absoluten und relativen Richtungs-Aenderun- 

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12. . — "Description of an Apparatus for Recording 



by Photography the Motions of Horizontal Pendulums." Seismol. Journ. of 

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13. . — " Horizontalpendel-Beobachtungen auf der 



Kaiserlichen Universitats-Sternwarte zu Strassburg, 1892-1894." Beitvdge 

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14. Safarik.—" A Contribution to the History of the Horizontal Pendulum" 



[trans.]. Phil. Mag., vol. xlvi., pp. 412-416 ; 1873. 



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Acad. Sci. Compt. Rend., vol. xcvii., pp. 229-234 (Delaunay's pendulum, 

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16. Zollner, F.— "On the Origin of the Earth's Magnetism, and the Magnetic 



Rotations of the Heavenly Bodies" [trans.]. Phil. Mag., vol. xliii., 

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C. Davison. 

 King Edward's High School, Birmingham. 



