[176]. “In order to carry on the parallel of latitude with as much expedition and economy as possible,” says Mr. Ellicott, “we dispensed with the method of tracing a line on the arc of a great circle, and correcting into the parallel; as pursued by Messrs. Mason and Dixon, in determining the boundary between this state” (Pennsylvania,) “and the state of Maryland, and which we followed in completing their line in the year 1784. We commenced our operations by running a guide-line, West, with a surveying compass, from the point mentioned on the Delaware” (the one which was fixed by Dr. Rittenhouse and Capt. Holland, in the year 1774,) 20¼ miles; and there corrected by the following zenith lines” (laid down in the sequel,) “taken, at its western termination, by a most excellent Sector, constructed and executed by Dr. Rittenhouse.”
[177]. The Liturgy of the Church of England was first translated into the Mohawk language, in the year 1714. Another translation was made under the direction of three clergymen of that church; namely, the Rev. Mr. William Andrews, Dr. Henry Barclay, and Dr. John Ogilvie: This was printed in the year 1769; but the place where it was printed does not appear. In the year 1787, an handsome edition of the English Book of Common Prayer, with a translation into the Mohawk language by captain Joseph Brant, was published in London.
[178]. Mr. Rittenhouse is not mentioned in the petition, by name. This was unnecessary: for it was universally known, that it could apply to no other person in America, so unquestionable and pointed are its allusions to him; and that, perhaps, no other Astronomer then living, so well merited the high encomiums on his philosophical abilities, which it contains.
[179]. Joseph Galloway and Samuel Rhoads, Esq’rs. the other vice-presidents of the society, were then members of the general assembly; and Dr. Franklin, the president, had not at that time returned from England. Mr. Rittenhouse was, at the same time, one of the curators of the society; as he was, also, during the year 1772.
[180]. That eminent mathematician and astronomer, Mr. Roger Cotes,[[180a]] in an excellent preface to his edition of Sir Isaac Newton’s Mathematica Principia Philosophiæ Naturalis, has explained the true method of philosophising; shewn the foundation on which the Newtonian system was built; and refuted the objections of the Cartesians, and all other philosophers, against it. In this preface, Mr. Cotes has ably answered those, who contended, that gravity or attraction, in the system of Newton, was not a clearer principle, nor one more fit to explain the phænomena of nature, than the occult qualities of the peripatetics: for, there were still philosophers, such as they were, who persisted in that absurd opinion! “Gravity,” said the objectors, “is an occult cause; and occult causes have nothing to do with true philosophy.” To which Mr. Cotes made this lucid reply:—“Occult causes are not those whose existence is most clearly demonstrated by observation and experiment; but those only whose existence is occult, fictitious, and supported by no proofs. Gravity, therefore, can never be called an occult cause of the planetary motions; since it has been demonstrated from the phænomena, that this quality really exists. Those rather have recourse to occult causes, who make vortices to govern the heavenly motions; vortices, composed of a matter entirely fictitious, and unknown to the senses. But, shall gravity therefore be called an occult cause, because the cause of gravity is occult, and as yet undiscovered? Let those who affirm this, beware of laying down a principle which will serve to undermine the foundation of every system of philosophy that can be established. For causes always proceed, by an uninterrupted connexion, from those that are compound, to those that are more simple; and when you shall have arrived at the most simple, it will be impossible to proceed further. Of the most simple cause, therefore, no mechanical solution can be given; for if there could, it would not be the most simple. Will you then call these most simple causes occult, and banish them from philosophy? You may so; but you must banish at the same time the causes that are next to them, and those again that depend upon the causes next to them, till philosophy, at length, will be so thoroughly purged of causes, that there will not be one left whereon to build it.”
The great doctrine of gravitation and attraction, the substratum of the Newtonian philosophy, is amply verified by numerous observations and experiments. Whether that which constitutes the principle of gravity be, in itself, an incorporeal or spiritual substance, or a materia subtilis, some very subtile kind of ethereal fluid, is a question which does not at all affect the actual existence of such a power. “We know,” as is observed by a great astronomer[[180b]] of our own time, “that all the bodies in our system are retained in their courses by such a power” (the power of attraction.) “And,” he adds, “it is a very singular instance of the unerring wisdom of the Creator, that the law which this power observes is such, that notwithstanding the mutual attractions of the bodies, the system will never fall into ruin, but is capable of preserving itself to all eternity. “Moreover,” continues the same profound writer, “the mutual attraction which takes place between distant bodies could not, of itself, either produce their motion about the sun, or the rotation about their axes: it required an external impulse to operate in conjunction with it, to produce these effects; an act, which nothing but the arm of Omnipotence could accomplish.” “An invisible power pervades the whole system, and preserves it. In the effects produced by man, we see the operation of the cause; but “the ways of the Almighty are past finding out.” “Hence,” says our author, “in whatever point of view we take a survey of our system, we trace the Power, Wisdom, and Goodness of the Creator: his Power, in its formation; his Wisdom, in the simplicity of the means to produce the ends; and his Goodness, in making those ends subservient to our use and enjoyment. Thus we are led by our enquiries into the structure of the universe, to the proofs of the existence and attributes of a Supreme Being, who formed and directs the whole. Arguments of this kind produce conviction which no sophistry can confound. “Every man may see it; man may behold it afar off.” Let not therefore the ignorant declaim against those pursuits which direct us to a knowledge of our Creator, and furnish us with unanswerable arguments against the infidel and the atheist.”
But, to return more immediately to the doctrine of gravitation: Some experiments had been made by M. Boguer and M. de la Condamine, so long since as the year 1738, upon the Chimboraso in South-America, in order to test the Newtonian theory of gravity, by examining the attraction of mountains; and the result accorded with that theory. With a view, however, to establish the principle more completely, the experiments of Messrs. Boguer and Condamine having been made under so many disadvantages, as rendered the result not sufficiently accurate to be entirely depended on, similar experiments were made upon the Mountain Schehallien in Scotland, by Dr. Maskelyne, at the request of the Royal Society, and under the patronage of his sovereign, the present king, who liberally undertook to defray the expenses. From observations of ten stars near the zenith, he found the difference of latitudes of the two stations on the opposite sides of the mountain to be 54″, 6; and by a measurement of triangles, he ascertained the distance of the parallels to be 4364, 4 feet, corresponding, in that latitude, to an arc of the meridian of 42″, 94, which is 11″, 6 less than by observation: its half therefore, 5″, 8, is the effect of the attraction of the mountain; and from its magnitude, compared with the bulk of the whole earth, Dr. Maskelyne computed the mean density of the latter to be about double that of the mountain. “Thus,” to use the words of Mr. Vince, “the doctrine of Universal Gravitation is firmly established.” The reader will find Dr. Maskelyne’s deductions from this experiment, in Vince’s Complete System of Astronomy, vol. ii. p. 100 and seq.
[180a]. This extraordinary man, who was the first Plumian professor of astronomy and experimental philosophy at Cambridge, was born July 10, 1682, and died prematurely June 5, 1716.
[180b]. The Rev. Mr. Vince, A. M. F. R. S. Plumian Professor of Astronomy and Experimental Philosophy, in the University of Cambridge. See his Complete System of Astronomy, vol. ii. p. 291.
[181]. The essay signed M. W. is dated from that place.