There frequently arises some uncertainty as to the precise time of birth, and some apprehensions lest it should not be accurately noted. In most cases, the actual minute of the hour, at which the birth happens, can only be ascertained by making a scientific observation, at the time, with an horoscopical astrolabe[112]; for all other instruments, employed in ascertaining the hour, are almost fallacious, although used by many persons with much care and attention. The clepsydra,[113] for instance, is subject to error, because the flow of the water will, from various causes, proceed irregularly: and the sundial is often incorrectly placed, and its gnomon often distorted from the true meridian line. To obviate the difficulty arising from the inaccuracy of these instruments, it seems highly necessary to present some method by which the actually ascending degree of the zodiac may be easily ascertained, in a natural and consistent manner. And in order to attain this essential point, it is necessary first to set down the ordinary degree which, by the Doctrine of Ascensions,[114] is found near the ascendant at the presumed hour. After this has been done, the new or full Moon, whichever it may be, that may take place next before the time of parturition, must be observed: and, if a new Moon, it will be necessary to mark exactly the degree of the conjunction of the two luminaries; but, if a full Moon, the degree of luminary only which may be above the earth during the parturition. After this, it must be observed what planets have dominion over the said degree: and their dominion depends always on the five following prerogatives, viz. on triplicity, house, exaltation, terms, and phase or configuration[115]; that is to say, a planet, eligible to dominion, must be connected with the degree in question either by one, or more, or all of these prerogatives. [112] It is, perhaps, needless to remark that modern improvements in science have superseded the use of this and other ancient instruments here mentioned. [113] Although the “clepsydra,” or water-clock, was commonly used among the ancients for various purposes, it appears, from Martian (a Latin writer, who lived about A. D. 490), that there was also a clepsydra in special use as an astrological engine. [114] “_The Doctrine of Ascensions_,” in allusion to the method of calculating the actual position of the ecliptic. [115] “_Phase or configuration._” Or, holding some authorized aspect to the degree in question. If, therefore, there may be found any one planet properly qualified in all or most of these prerogatives, the exact degree, which it occupies in that sign in which it may be posited during the parturition, is to be remarked; and it is then to be inferred that a degree of the same numerical denomination was actually ascending, at the precise time of birth, in that sign which appears, by the Doctrine of Ascensions, to be nearest to the ascendant.[116]