renders the improvement of time keepers an object of the greater importance.

Many other schemes and proposals have been made by different persons, but most of them of very little or no use; such as by the space between the flash and report of a great gun, proposed by Messrs Whiston and Ditton; and another proposed by Mr. Whiston, by means of the inclinatory or dipping needle; besides a method by the variation of the magnetic needle, &c, &c.

Longitude of Motion, is a term used by Dr. Wallis for the measure of motion, estimated according to its line of direction; or it is the distance or length gone through by the centre of any moving body, as it moves on in a right line.

The same author calls the measure of any motion, estimated according to the line of direction of the vis motrix, the Altitude of it.


, a learned astronomer, born in Denmark in 1<*>62, in the village of Longomontum, whence he took his name. Vossius, by mistake, calls him Christopher. Being the son of a poor man, a plowman, he was obliged to suffer, during his studies, all the hardships to which he could be exposed, dividing his time, like the philosopher Cleanthes, between the cultivation of the earth and the lessons he received from the minister of the place. At length, at 15 years old, he stole away from his family, and went to Wiburg, where there was a college, in which he spent 11 years; and though he was obliged to earn his livelihood as he could, his close application to study enabled him to make a great progress in learning, particularly in the mathematical sciences.

From hence he went to Copenhagen; where the professors of that university soon conceived a very high opinion of him, and recommended him to the celebrated Tycho Brahe; with whom Longomontanus lived 8 years, and was of great service to him in his observations and calculations. At length, being very desirous of obtaining a professor's chair in Denmark, Tycho Brahe consented, with some difficulty, to his leaving him; giving him a discharge filled with the highest testimonies of his esteem, and furnishing him with money for the expence of his long journey from Germany, whither Tycho had retired.

He accordingly obtained a professorship of mathematics in the university of Copenhagen in 1605; the duty of which he discharged very worthily till his death, which happened in 1647, at 85 years of age.

Longomontanus was author of several works, which shew great talents in mathematics and astronomy. The most distinguished of them, is his Astronomica Danica, first printed in 4to, 1621, and afterwards in folio in 1640, with augmentations. He amused himself with endeavouring to square the circle, and pretended that he had made the discovery of it; but our countryman Dr. John Pell attacked him warmly on that subject, and proved that he was mistaken.——It is remarkable that, obscure as his village and father were, he contrived to dignify and eternize them both; for he took his name from his village, and in the title page to some of his works he wrote himself Christianus Longomontanus Severini filius, his father's name being Severin or Severinus.

LOXODROMIC Curve, or Spiral, is the same as the Rhumb line, or path of a ship sailing always on the same course in an oblique direction, or making always the same angle with every meridian. It is a speciea of logarithmic spiral, described on the surface of the sphere, having the meridians for its radii.


, the art or method of oblique sailing, by the loxodromic or rhumb line.


, an oblique-angled parallelogram; being otherwise called a rhombus, or a rhomboides.


, a Polish gentleman, born at Cracow, in 1623, and educated with great care by his father. He was learned in astronomy, and became a celebrated Socinian minister. He took great pains to obtain a toleration from the German princes for his Socinian brethren. His endeavours however were all in vain; being himself persecuted by the Lutheran ministers, and banished from place to place; till at length he was banished out of the world, with his two daughters, by poison, in 1675, his wife narrowly escaping.

We have, of his writing, A History of the Reformation in Poland; and a Treatise on Comets, intitled Theatrum Cometicum, printed at Amsterdam in 2 volumes folio; which is a most elaborate work, containing a minute historical account of every single comet that had been seen or recorded.

LUCIDA Coronæ, a fixed star of the 2d magnitude, in the northern crown. See Corona Borealis.

Lucida Hydræ. See Cor Hydræ.

Lucida Lyræ, a bright star of the first magnitude in the constellation Lyra.


, a name given to the planet Venus, when she appears in the morning before sunrise.


, a term used for the sun and moon, by way of eminence, for their extraordinary lustre, and the great quantity of light they give us.


, the Moon; which see.


, something relating to the moon.

Lunar Cycle, or Cycle of the Moon. See Cycle.

Lunar Method for the Longitude, a method of keeping or finding the Longitude by means of the moon's motions, particularly by her observed distances from the sun and stars; for which, see the article LONGITUDE.

Lunar Month, is either Periodical, Synodical, or Illuminative. Which see; also Month.

Lunar Year, consists of 354 days, or 12 synodical months, of 29 1/2 days each. See Year.

In the early ages, the lunar year was used by all nations; the variety of course being more frequent and conspicuous in this planet, and consequently better known to men, than those of any other. The Romans regulated their year, in part, by the moon, even till the time of Julius Cæsar. The Jews too had their lunar month and year.

Lunar Dial, Eclipse, Horoscope, and Rainbow. See the several substantives.


, the period or time between one new moon and another; it is also called the synodical month, consisting of 29 days 12 hrs. 44m. 3 sec. 11 thirds; exceeding the periodical month by 2 ds. 5 hrs. 0 m. 55 sec.


, or Lunula, or little moon, is a geometri-