equatorIal, tequatoreal

& s. [Fr. équatorial, from Lat. equator (gen it, equator is ) [EQUATOR], and Eng., Fr., ., suff. -al.] A. As adjective : In any way pertaining to the astronomical, the geographical, or the magnetical equator. "Exce of the equatorial above the polar radius."_ Malte Brun: Physic. Geog. (2d ed., 1834), p. 59. B. As subst.: An astronomical instrument designed to note the course of the stars as they move through the sky. A strong axis is constructed and permanently fixed in a slanting position so as to point exactly to the North Pole of the heavens. It turns upon its axis, carrying with it a telescope which, if it retained its relative position to that of the revolving portion of the instrument, would enable an observer looking through it to see no more than a single great circle of the sky. It is not, how ever, fixed to the revolving portion of the instrument, but may be moved up or down so that with it an astronomer can follow the entire course of a circumpolar star in its pa age around the sky. It is of importance to ascertain not only the course of a star, but the apparent rapidity of its movement. This end is attained by attaching to the axis of the equatorial a racked wheel in which works an endle screw or worm, the whole put in motion by an apparatus furnished with centrifugal balls, like those of the governor of a steam-engine, and which render the motion uniform. The tele at scopes in the equatorials used well-equipped which an astronomer may wish to observe. He has but to bring the star within the field of telescopic vision, and machinery will keep it there hour after hour without any further attention on his part. ( Prof. Airy : Popular Astron . (6th ed.), pp. 8 to 12.) equatorial-current, 8. Hydrol.: A current in the ocean which cro es the Atlantic from Africa to Brazil, having a breadth varying from 160 to 450 nautical miles. Its waters are cooler by 3° or 4° than those of the ocean under the line. Its effect, therefore, is to diminish the heat of the tropics. ( Lyell : Principles of Geology, ch. vii.) An instrument of large