Imágenes de páginas
PDF
EPUB

Horizontal Moon, &c. The fixth chapter fhcws the mes thod of finding the distances of the sun, moon, and planets. The seventh contains an explanation of the different lengths. of days and nights; the vicissitudes of seafons; and the phænomena of Saturn's ring. In the eighth chapter we have the method of finding the Longitude by the eclipses of Jupiter's Satellites, and a demonstration of the amazing velocity of light by these eclipfes; together with a table for converting mean solar time into degrees and parts of the terreftial Equator, and also for converting degrees and parts of the Equator into mean folar time.

The ninth chapter treats of the phenomena of the heavens, as seen from different parts of the solar system, and the tenth of solar and fidereal time; the Equation of natural days; and Recession of the Equinoxes. In this chapter we have a table fhewing how much of the Celestial Equator paffes over the Meridian in any part of a mean solar day; and how much the fixed the stars

gain upon

the mean solar time every day, for a month.

This chapter" likewise contains a table of the Equation Time depending on the sun's place in the ecliptic; a tablous the Equation of Time, depending on the sun's anomaly; 2 table shewing the Precession of the Equinoxes ; a tablo exhia, biting the difference between Sidereal, Julian, and Solar jeans with tables of the Equation of Natural Days; al very esat and accurate. In the eleventh chapter Mr. Ferguson explains the phænomena of the Harvest Moon, in a very clear and tisfactory manner: and in the twelfth he describes the moon's surface and her phases.

In the thirteenth chapter Mr. Ferguson explains the theory of the tides on the Newtonian principles; and in the fourteenth treåts of eclipses, their number and periods. He likewise presents us with a large catalogue of ancient and modern ecliples, from Struyk and Ricciolus ; and endeavours to ascertain the true time of our Saviour's crucifixion.

• There is a remarkable prophecy,' says he, 'in Daniel, chap. ix. ver. 26, 27. concerning the year in which the • Messiah should be cut off. And he shall confirm the covenant

with many for one week; and in the midst of the week he shall cause the sacrifice and the oblations to cease. Now, as it is generally allowed, that by each of Daniel's prophetic weeks was meant seven years, the middle of the week must be in

the fourth year. And as our Saviour did not enter upon his ' public ministry, or confirming the covenant, until he was Rev. Sept. 1756.

R

• baptized,

was

[ocr errors]

• baptized, which, according to St. Luke, chap. iii. ver. 23.

in the beginning of his thirtieth year, or when he was « full twenty-nine years old ; this prophecy points out the ve

ry year of his death; namely, the thirty-third year of his age, or fourth year of his public ministry. Let us now try whether we can ascertain that year from astronomical principles and calculations. • The Jews measured their months by the moon, and their years by the revolution of the sun; which obliged them either to intercalate eleven days at the end of every

twelve • months ; or a whole month (which they called Ve-Adar)

every third year : for twelve lunar months want almost eleven days of twelve months measured by the fun. • In the year of the crucifixion, the Passover full-moon was

on a Friday; for our Saviour fuffered on the day next be<fore the Jews Sabbath. Here we have the day of the week

afcertained, St. Mark, chap. xv. ver. 42. St. Luke, chap. 6 xxiii. ver. 54.

• As the lunar year falls eleven days short of the solar, the • full moon in any given month must, at the annual return of

that month, be eleven days sooner ; and, consequently, cannot fall

again upon the same day of the week: for eleven days measure a week, and four days over. Hence, if the . April full-moon this year, for example, be on a Sunday, on & the next year it will be on a Thursday; unless the next be

a Leap-year, which will cause twelve days difference; and oso, counting backward, throw it on a Wednesday.

Thus, it is plain, that in different neighbouring years, the Passover full-moons must be on different days of the * week, unless when the Passover months themselves are dif« ferent: that is, when the full-moon happens between the

Vernal Equinox and first day of April, the Passover falls in • March ; but always in April when no full-moon happens

within this limit. • Now, if it can be proved, that there was but one Passover full-moon on a Friday in the course of a few years, about which we imagine the year of the crucifixion to have been, as it is generally allowed that our account is not above

four or five years wrong at moft; that year on which the • Passover full-moon fell on a Friday, must undoubtedly be

the year fought. • In order to determine this, I first went to work with my orrery; which, in two or three minutes may be rectified to as to thew the days of the months answering to all the new

o the

6 and full moons and eclipses, in any given year, within the

limits of fix thousand years both before and after the Christian Æra: and when once set right, will serve for above three hundred years without any new rectification. I began with the twenty-first year after the common date of our Saviour's birth, and observing from thence, in every year to the fortieth, was surprised to find, that inthe whole course of twenty years fo run over, there had been but one Pasover fullmoon on a Friday : and that one was in the thirty-third year of our Saviour's age, not including the year of his birth,

because it is supposed he was born near the end of that year, • But that it might not be said I trusted to the mechanical

performance of a machine, I computed all the Palover fullmoons (according to the precepts delivered in the following chapter) from astronomical tables, which begin not with

year of our Saviour's birth, but the first year after it; • and found, as a thing very remarkable, that the only Paff

over full-moon which happened on a Friday in all that time, 'was in the thirty-third year of his age by the tables, or fourth

year of his public ministry, agreeable to the afore-mention• ed remarkable prophecy.

We shall here fubjoin a table of the true times of all the conjunctions of the sun and moon (adapted to the Meridian of Jerusalem) which preceded the Paffover full-moons, from A. D. 28, to A. D. 36 inclusive, although it be more than double the number that there is occasion to examine for our present purpose. All these new moons fell in Pisces and

Aries, which figns set at a greater angle with the horizon in o the west than any others; and therefore, a few degrees of

them take more time to go down. Now, the moon movès i fomewhat more than twelve degrees from the fun in twenty-. 6 four hours; and if two small patches be put twelve degrees

asunder, upon any two parts of Pisces or Aries, in the eclip

tic of a common globe, and the globe rectified to the lati"tude of Jerusalem, the most easterly patch representing the

moon, will be an hour later of setting than the other which

represents the sun: consequently, in that latitude the moon • may be seen juft setting about an hour after the sun, when • she is not above twenty-four hours old. And fourteen days

added to the day of this first appearance after the change, ' gives the day of full-moon.

[ocr errors]
[blocks in formation]

28 Mar. 15

I

4 Mor. 7 30 Afte.

I 51 Mor.

April 3.
Mar. 23
Mar. 13.
Mar. 31.
Mar. 20.
Mar. 10.
Mar. 29.

5 12 Mor.

True Time of Conjuncti- Moon visible at Jewish Full

on at Jerusalem. Jerusalem. Moon. A.D. D. H. M.

D.

Mar. 16. Mar. 31 Wednef. . 29 April 2.

Apr. 17 Sunday. 30 Mar. 22. 8 45 Afte.

Apr. 6 Thursa. 31 Mar. 12.

Mar. 27 Tuesd. 32 Mar. 29. II 19 Afte.

Apr. 14 Mond. *33 Mar. 19. I 12 Afte.

Apr. 3 Friday. 34 Mar. 9.

Mar. 24 Wednef. 35 Mar. 28. 6 20 Afte.

Apr. 12 Tuela. 36 Mar. 16. 6 30 Afte. Mar. 17. Mar. 31 Saturd.

The above thirty-third year was the 4746th year of the • Julian period, and the last year of the 2020 Olympiad; · which is the very year that Phlegon informs us an extraor

dinary eclipse of the fun happened. His words are, In the fourth year of the 2020 Olympiad there was the greatest eclipse of the fun that ever was known: it was night at the fixth

hour of the day, so that the stars of heaven were seen. This « time of the day agrees exactly with the time that the dark• ness began, according to Matihew, chap. xvii. ver. 25. « Mark, chap. xv. ver. 33. and Luke, chap. xxiii. ver. 44. • But whoever calculates, will find, that a total eclipse of the « fun could not possibly happen at Jerusalem any time that year in the natural way.

All this seems sufficient to ascertain the true time of our « Saviour's birth and crucifixion to be according to our pre< sent computation; and to put an end to the controversy a• mong Chronologers on that head. From hence likewife

may be inferred the truth of the prophetic parts of scripture, < since they can stand so strict a test as that of being examined

on the principles of Astronomy.'

The fifteenth chapter shews the method of calculating new and full moons, that of calculating and projecting folar and lunar eclipses, the use of the Dominical Letter, and contains feveral astronomical and chronological tables. In the sixteenth chapter we have a description of several astronomical machines, which serve to explain and illustrate the foregoing part of the treatise. These machines are--the Orrery, fronting the title-page, made by the Author ; the Calculator, contrived by Mr. Ferguson to explain the harvest mcon; the Cometarium, a curious machine invented by Dr. Delaguliers,

for

for shewing the motion of a comet, or excentric body moving round the sun, describing equal areas in equal times; the improved Celestial Globe; the Planetary Globe; the Trajectorium Lunare, for delineating the paths of the earth and moon, Thewing what sort of curves they make in the etherial regions; the Tide-Dial; and the Ecliplareon, a piece of me. chanism that exhibits the time, quantity, duration, and progress of solar eclipses, at all parts of the earth.

Having thus given our readers a general view of what is contained in this performance, we shall conclude with observing, that though it is chiefly calculated for such as have not studied Mathematics, those who have even made a considerable progress in mathematical studies will, nevertheless, find it worthy of their attentive perulal.

The Method of Fluxions applied to a select Number of useful

Problems : together with the Demonstration of Mr. Cotes's Forms of Fluents, in the second part of his Logometria ; the Analysis of the Problems in his Scholium Generale ; and an Explanation of the principal Propositions of Sir Isaac Newton's Philosophy. By Nicholas Saunderson, L. L. D. late Professor of Mathematics in the University of Cambridge, 8vo. 6s. Millar.

F all the surprising phænomena that have, in different

,

one more difficult to be accounted for, than that of a blind man's excelling in the most difficult and sublime parts of the Mathematics. It seems, indeed, almost impossible ; and had not the present age afforded us the illustrious example of Profeffor Saunderfon, we might, perhaps, have looked upon the instances of his kind, related by authors, as fictions; or, at least, that they had greatly magnified the truth. The most remarkable of such instances, mentioned by historians, is that of Dydimus of Alexandria, who, “ tho'blind* from his in“ infancy, and consequently ignorant of the very letters, ap

peared so great a miracle to the world, as not only to learn “ Logic, but also Geometry to perfection, which seems the most of any thing to require the help of sight.” The case of this extraordinary person, is similar to that of our Author, who, “ when † twelve months old, was deprived by the small

[merged small][merged small][ocr errors]
« AnteriorContinuar »