YOJANA or Ved. SANSK. Au astronomical and geographical measure, deduced from the ratio of the diameter of the earth to the circumference of its equatorial circle. The dimensions of the yojana, like those of any other measum, miginate in an arbitrary division of extent, for wfiich the Hindus have chosen a finger or angula as `a. standard to be found in nature. By that common measure they estimate not only distances and the dimen sions of the earth, but even the distariec of the planets, their parallaxes, and (when referred to particular points on the surface of the earth) the effects of their longitude and latitude as to thne. The Hindu mathematicians divide the diameter of the earth into 1600 parts, whence they have this expression At 10 X 1600 = 50596 yojana for the value of the equatorial circle. An angle of one miuute of a degree is supposed to be sub tended by 15 yojana, at the mean distance of the moon ; so that, dividing the earth's semi-diameter (800 yojana) by 15, we have 53' 20" for the moon's mean horizontal parallax. It follows from this result that 53' 20" of the moon's orbit will measure 15 yojana, and that her whole orbit (360°) will measure 324000 yojana. Hence 5059 (the circumference of a great circle of the terrestrial globe in yojana) is to 800 yojana (its semi-diameter) as 324000 (the circumference of the moon's orbit in yojana) is to 51235 yojana, her mean distance from the earth, from which it follows that this distance (according to the esti mate of Hindu astronomers) is about 64 semi diameters of the earth. As the moon is supposed
to complete 57753336000 sidereal revolutions in calpa, this number drawn into 324000, gives 18712080864000000 yojana for her absolute motion during that time. It is a principle in Hindu. astronomy that the absolute motion of each planet in a day, or any other time given, is equal to the absolute motion of the moon in the same time. Hence, if the absolute motion of the moon during a calpa be divided by the number of mean revolutions completed by any planet, during that period it will give the cacsha or circumference of the planet's orbit in yojana. To convert degrees of latitude and longitude into yojana, they use the following proportion : As 360 °to the proposed number of degrees, so 5059 yojana (the circumference of the equatorial circle) to the number of yojana sought. The Hindus sub divide the yojana into a great number of parts, in the following manner :—The yojana 4 crosa 1000 dhanush or clanda ÷ 4 resta or cubits 2 vitisti or spans+ 2 pada or foot-breadths ÷ angula or finger-breadths -:- 4 yara. Some make the crosa =2000, danda or half a yojana, which agrees.better with that in which the distances are usually computed. The yojana is regarded in Ceylon as being equal to 16 English miles. — Hardy's Eastern Illonachistn, p. 443 ; Warren, ICala Sankalita.