« VorigeDoorgaan »
made plain to those who are not, as follows:-If two lines, CA and CB, be taken, inclined to one another at an angle, ACB, equal to the sum or difference of the latitudes, and as many equal parts be measured off from CA as there are miles in the corresponding radius of the earth, and as many from CB as in the radius corresponding to B; also, if at the points B and A, thus determined, lines, As and Bs, be drawn inclined to AC and AB at angles equal to the observed zenith distances, ZAS and z'BS, then the lines As and BS will meet in some point, s, determined by the conditions under which the figure has been constructed; and this point s will hold the same position in respect to A and B and c that the sun does in respect to the two places of observation and the earth's centre. If, then, we find how many of the equal parts used there are in sc, we shall know the number of miles
which the earth's centre is distant from the sun.
The method which has been described is one of the least artificial that can be conceived. In actual practice the compass and rule would fail us for want of accuracy, and even calculations thus made would not give even an approximation to the truth, by reason of the great length of SA and SB as compared with CA and CB. We must, therefore, have recourse to trigonometry, by a very simple operation of which we shall be enabled to determine sc, knowing CA, CB, BCA, Z'BS, and ZAS. It is thus ascertained that the mean distance of the sun is 23984 radii of the earth, or that sc is 23984 times AC. This result is confirmed by other and independent observations and calculations of a more complicated, and of a more accurate nature. We may, therefore, assume as a result, which cannot possibly be in error beyond certain known, and those comparatively very narrow limits, that the sun is distant from us 95 millions of miles. The greatest diameter of the earth's orbit is equal to twice its mean distance, or 47,968 radii of the earth. Now it has been shown that the sun's distance from the two extremities of this orbit are in the ratio of 32,593 to 31,517; this being the ratio of its apparent diameters in aphelion and perihelion, we have only then to divide the number 47,968 into parts which are in the ratio of 32,593 to 31,517, and we obtain for the earth's distance in aphelion 24,388 radii of the earth; and for its distance in perihelion 23,580 radii. Knowing, thus, the position of one of the foci of the earth's orbit, and the length of its greater diameter, we can determine all its dimensions. Thus, then, the magnitude of the earth's orbit is completely known.
THE PLANE OF THE EARTH'S ORBIT.
IN our reasonings hitherto we have supposed the observer to occupy a position on the earth's surface, and everything presented to him under
these circumstances has necessarily been presented under a complicated form, combining with its proper motion another apparent motion, arising from a continual change in the observer's point of view; to separate these two motions is a distinct operation of the mind, and one of considerable effort.
The mind may now, however, take up a new position in the universe, and in imagination move at will on the surface of a fixed invariable plane, that of the earth's orbit, which when produced in the vault of the heavens, traces out there the ecliptic. Let a line be drawn perpendicular to this plane through the sun, and it will mark on the heavens a point called the pole of the ecliptic; great circles of the heavens drawn through this pole perpendicular to the ecliptic are called circles of celestial latitude, and the latitude of any point in the heavens is the number of degrees between that point and the ecliptic, measured on one of these circles.
If a line be drawn through the sun parallel to the direction of the earth's axis, and through this line a plane perpendicular to the plane of the earth's orbit, this plane will intersect,-the heavens in a circle called the solstitial colure,—and the line of the earth's orbit in the points which we have before shown to be those occupied by its centre at the solstices*—and the celestial ecliptic in two points called Cancer and Capricorn V8, in which points of the heavens are the sun's apparent places at the time of the solstices. If from these points were measured off 90 degrees both ways on the ecliptic, we shall determine two points in it called the equinoctial points, and, where the sun appears on the equinoxes. The number of degrees from Aries eastward of the point where the circle of latitude of any place in the heavens cuts the ecliptic, is called the longitude of that place of the heavens.
Thus, if NESW be the intersection of the plane of the earth's orbit CD with the sphere of the heavens, it will be the celestial ecliptic, and if s be perpendicular to this plane, п will be its pole. If AB be parallel
* These are the northern and southern points of the earth's orbit.
to the earth's axis, and the plane ПIвNS perpendicular to S KN, the intersection, s II N, of this plane with the sphere of the heavens will be the solstitial colure, and s and N will be the solstices Capricorn vs and Cancer, and the south and north points of the ecliptic; 90 degrees from these will be the points and, of which the former is the western and the latter the eastern point of the ecliptic. The latitude of any point o of the heavens is the arc σ K, and its longitude the arc o N K, or the angle SK.
The sphere of the heavens which we are now describing is in reality a different one from that before spoken of; that sphere had its imaginary centre in the centre of the earth; this has for its centre the centre of the sun; so that the centre of its former sphere was in motion, and its motion was perpetually round the centre of this sphere. But it was shown that the radius of the circle in which this motion takes place is infinitely small as compared with the radius of the great sphere of the heavens ; so that, so far as the appearance of objects on its surface was concerned, it might be considered to be at rest. So far as the appearance of these objects are concerned, it may therefore be supposed to coincide with the centre of that sphere of which we are now speaking. Considering then the centres and surfaces of these spheres to coincide, we shall have two sets of lines on the celestial sphere, the one having reference to the equinoctial, and the other to the ecliptic, and two poles, one being that of the former, and the other of the latter. The right ascension and declination of any heavenly body or point in the heavens is measured and fixed by means of the former set of lines, precisely as its longitude and latitude are by means of the latter.
GEOLOGY AND THE HOLY SCRIPTURES.
[We have received from a reverend gentleman, highly distinguished both for his piety and his learning, the following communication on the subject of our review of DR. BUCKLAND's Bridgewater Treatise. As a scriptural and philological argument, it might, by strict construction, be deemed somewhat out of place in the Magazine of Popular Science; but a consideration of the importance of the subject, and the interest which it is peculiarly calculated to excite in the minds of religious readers, particularly when so able and influential a person as the writer of this paper has entered into the discussion in our own pages, have decided us to waive this distinction, and to present it to our readers, without remark or comment.]
To the Editor of the Magazine of Popular Science.
SIR,-With cordial approbation of the design and the general execution of your article, in the last month, upon Dr. Buckland's Bridgewater Treatise, I request your candid indulgence of some brief remarks.
The observations in pp. 337-339, appear to me capable of being misunderstood, or of being construed injuriously in various ways to the interests of both science and religion. The tendency of those observations appears to be, First, to assume (or at least to warrant the assumption) that the Holy Scriptures contain allegations and implications with respect to the natural history of our earth, which are contradicted and disproved by the demonstrations of modern geology; and, Secondly, that it is the duty of a philosopher to abstain from any discussion of this discrepancy, and from any inquiry whether it be real or only apparent: as if it were said, Let these two branches of knowledge be kept far away from each other let philosophers and geologists pursue their own course, and let theology and religion practise their own duties, and watch over their own interests; but let neither interfere with the other; let no inquiry ever be made whether they are in accordance or in opposition.
This short way of dismissing the matter has, indeed, been adopted by some eminent men; but I appeal, Sir, to your impartial reflection, whether it is not absurd and impracticable.
1. It is absurd. TRUTH throughout her whole domain, illimitable as is its extent, is one in principle, and harmonious in details. It is no other than the having our conceptions in accordance with the reality of things. And Truth in expression (= veracity) is the adapting of our language, written or spoken, to the honest utterance of our conceptions. A mere child, if he will reflect a moment, perceives that a proposition cannot be true and false, under the same circumstances; unless there be some artifice practised in the use of terms. An assertion cannot be true in theology, and false in geology, or any department whatever of scientific knowledge; nor inversely. It really is an insult tó men's understandings, to admit indirectly, that there are affirmations or doctrines in the records of revealed religion, which are disproved by the clearest evidence of science; and then to proscribe investigation, with a solemn pretence of mysteries not to be inquired into, an hypocritical tone of reverence for sacred things. The veil is transparent; no man can be deceived by it: but it is lamentable that any should attempt to VOL. II.
deceive by it. We greatly wrong the interests of knowledge, and prejudice our own improvement, when we but seem to admit that theology is an insulated portion of science, which may be safely pursued by itself, and which yields no advantages to other departments. True theology, on the contrary, attracts to itself, illustrates, and harmonizes all other knowledge. It is the science which relates to the Author and Preserver of the whole dependent universe; whatever may be known concerning HIM, for the noblest purposes of intellectual improvement, of personal virtue, and of diffusive happiness. It is formed by strict induction from the works and the word of God; natural notices, and positive revelation. It is the friend of all science; it appropriates all truth; it holds fellowship with no error.'
2. It is impracticable. This kind of ban upon a reasonable, an inevitable query, is never submitted to by any person of sound understanding. Either he receives the assumption,-and, as its consequence, he rejects covertly or openly the truth and authority of the Bible; or he searches out the matter fairly and fully, and then he learns that the assumption is false.
Is it then the fact, that such fair and impartial inquiry will bring out this result? Is it, after all, an erroneous assumption, that the declarations of Scripture and the sensible demonstrations of geological science, pointedly contradict each other? Does not the Bible teach that the moment of the Supreme Being's first putting forth his creating power, was only about six thousand years ago? And do not the undeniable phenomena of stratification, and other facts, demonstrate that our globe (to say nothing of the rest of the solar system, and the astral universe,) has existed, has passed through countless changes, such as are continually in progress, and others of a more intense character, which rational estimation must suppose to have required a period for their production so vast as to fill us with astonishment,-which no calculator ventures to lay down, which probably amounts to millions and millions of years?
Fully admitting the assumptions in the last query, I deny that of the preceding one.
It is to be lamented that the common habits of expression nourish the opinion, that the authority of Scripture maintains the commencement of dependent nature to have been as has been stated and it is scarcely less to be lamented that theories have been propounded for conciliating the facts of nature and the Scripture narrative, which rest upon either a defective acquaintance with those facts, or a disregard to the plain use of language in that narrative. Of the former kind are the schemes for finding the time requisite for the terrene formations, in the period from the creation of the first man, to the Noachian deluge; of the latter, those which interpret the days of successive operation, laid down in the primeval record, as if they were indefinite periods.
It will appear evident to any one who will reflect upon the case, that the records of revelation must have been written in the phraseology and idioms of the people and the age to which they were given; or they would have been unintelligible. Upon this principle we account for the manner in which natural phenomena are currently described; and for the expressions which impute to the Infinite Spirit the form, the organs,