Penn History

The Relation of David Rittenhouse
and His Orrery to the University

By M. J. Babb
originally published in the General Magazine and Historical Chronicle. Date unknown.
Rittenhouse Orrery at
Van Pelt Dietrich Library Center detail of Orrery, center panel

The name Orrery comes from the following train of facts. When George Graham, the celebrated London mechanic and watchmaker, employed one Rowley to construct his planetarium, said Rowley retained a model, and was afterward patronized by Charles Boyle, Earl of Orrery, in making a large machine which, though only representing one or two of the heavenly bodies, was sold to George the First for a thousand guineas. Sir Richard Steele in the work entitled "A New and General Biographical Dictionary", published in 1761, attributed this invention to the Earl of Orrery. Hence compilers of the British Encyclopaedia, which was republished in Philadelphia, followed his lead and such machines have since been known as Orreries. The new Zeiss planetarium coming to Philadelphia within the year as the magnificent gift or Mr. Samuel Fils is a direct descendant of these Orreries.

The work of the colonial clockmakers led by the Stretch's and Duffield was surpassed by Rittenhouse who was evolving astronomical instruments, to take the place of the globes of Theophilus Grew, first Professor of Mathematics at the Academy of Philadelphia.

When David Rittenhouse conceived of his Orrery sometime before 1767, Rev. Thomas Barton had undertaken to indemnify him for such expenditures as he should incur, not exceeding a stipulated sum, should he be not able to dispose of it for a set price. Thomas Barton thus established the first research fund in this state. In a letter to Barton of January 28, 1767, Rittenhouse described all types of Orreries listed by Martin, Rowning and others and says:

I will have no circles except the zodiac, on which I will have the true latitude and longitude of each planet pointed out by its proper index. I did not design a machine which should give the ignorant in astronomy a just view of the Solar System: but would rather astonish the skilful and curious examiner, by a most accurate correspondence between the situations and motions of our little representatives of the heavenly bodies, and the situations and motions of those bodies, themselves. I would have my Orrery really useful, by making it capable of informing us, truly, of the astronomical phaenomena for any particular point of time; which, I do not find that any Orrery yet made, can do.

Mr. Barton replied February 21, 1767:

Dear Brother,
I received a few days ago, yours of the 28th ult.--after it had undergone the torture of some Dutchman's pocket, which compelled it to force its way through the cover: However, the inside did escape without many fractures; so that I had the pleasure of getting it into my hands in such a condition that I could read it. * * * I would have you pursue your Orrery in your own way, without any regard to an ignorant or prevailing taste. All you have to study is truth, and to display the glorious system of Copernicus in a proper manner;--and to make your machine as much an original, as possible. I beg you will not limit yourself in the price. I am now perfectly convinced, that you can dispose of it to advantage; and should be sorry you would lose one hour more in fears or doubts about it. In fact, I have laid such plans for the disposal of it, that I have almost a moral certainty of having a demand for more than one of the kind. I have not time to write you as fully as I could wish, as the transcribing from Rowning has detained me so long, and I am this moment setting out for Caernarvon. My letter to the Propretor is delayed, till I can send him the account of your design, which you are pleased to promise me. You say you have 'a specimen' in hand: I should be glad to know what it is. * * * I am, in haste, dear Davy, your very affectionate friend and brother,
Thomas Barton.

P.S. I beg leave to recommend Huygens', Cotes', Helsham's, and Power's Philosophy to you. You will be much pleased with them. I wish you would purchase Bion's Description of Philosophical and Mathematical Instruments, &c.

Rittenhouse's description of his Orrery to Mr. Barton differs somewhat from that in the American Philosophical Society's Transactions. He wrote as follows:

Description of a New Orrery

This Machine is intended to have three faces, standing perpendicular to the horizon: that in the front to be four feet square, made of sheet-brass, curiously polished, silvered, and painted in proper places, and otherwise ornamented. From the centre arises an axis, to support a gilded brass ball, intended to represent the Sun. Round this ball move others, made of brass or ivory, to represent the Planets: They are to move in elliptical orbits, having the central ball in one focus; and their motions to be sometimes swifter, and sometimes slower, as nearly according to the true law of an equable description of areas as is possible, without too great a complication of wheel-work. The orbit of each Planet is likewise to be properly inclined to those of the others; and their Aphelia and Nodes justly placed; and their velocities so accurately adjusted, as not to differ sensibly from the tables of Astronomy in some thousands of years.

For the greater beauty of the instrument, the balls representing the planets are to be of considerable bigness; but so contrived, that they may be taken off at pleasure, and others, much smaller, and fitter for some purposes, put in their places.

When the Machine is put in motion, by the turning of a winch, there are three indexes which point out the hour of the day, the day of the month, and the year (according to the Julian account,) answering to that situation of the heavenly bodies which is then represented; and so continually, for a period of 5000 years, either forward or backward.

In order to know the true situation of a Planet at any particular time, the small set of balls are to be put each on its respective axis; then the winch to be turned round until each index points to the given time. Then a small telescope, made for the purpose, is to be applied to the central ball; and directing it to the planet, its longitude and inclination will be seen on a large brass circle, silvered, and properly graduated, representing the zodiac, and having a motion of one degree in seventy-two years, agreeable to the precession of the equinoxes. So, likewise, by applying the telescope to the ball representing the earth, and directing it to any planet,--then will both the longitude and latitude of that planet be pointed out (by an index and graduated circle,) as seen from the earth.

The two lesser faces are four feet in height, and two feet three inches in breadth. One of them will exhibit all the appearances of Jupiter and his Satellities--their eclipses, transits, and inclinations; likewise, all the appearances of Saturn, with his ring and satellites. And the other will represent all the phenomena of the moon, particularly, the exact time, quantity, and duration of her eclipses-and those of the sun, occasioned by her interposition; with a most curious contrivance for exhibiting the appearance of a solar eclipse, at any particular place on the earth: likewise, the true place of the moon in the signs, with her latitude, and the place of her apoge in the nodes; the sun's declination, equation of time &c. It must be understood, that all these motions are to correspond exactly with the celestial motions; and not to differ several degrees from the truth, in a few revolutions, as is common in Orreries. If it shall be thought proper, the whole is to be adapted to, and kept in motion by, a strong pendulum-clock; nevertheless, at liberty to be turned by the winch, and adjusted to any time, past or future.

N.B. The diurnal motions of such planets as have been discovered to revolve on their own axes, are likewise to be properly represented; both with regard to the Times, and the situation of their Poles.

This description was sent to Mr. Barton March 27th, 1767- We will amplify this description somewhat as follows:

The main face has the planets Mercury, Venus, Earth, Mars, Jupiter and Saturn accompanied by their satellites as known before Herschel. The planets are at distances approximately 1/4", 1-11/32", 1-13/16", 3", 9-13/16", 18-1/4" from t he center of the Sun. The first three are on solid cams, while the last three are on what might be termed hands. Both hands and cams turn in their proper ecliptic planes. Both planets and satellites are perfectly timed in their revolutions. The zodiac is represented by a large, slowly moving circle about the whole. The part containing the moon has at the top in the form of a spiral the 1461 days of three ordinary and one leap year arranged around a circle containing 487 days. Hands point to the year, month and day, and below is another dial registering the hours. The lower part of this face contains an arrangement somewhat like an ordinary cheese box. The zodiac is on the rim of this, which of course revolves as above. The inside of the curved surface is silvered and divided into 360° of azimuth, and below a central line are five degrees of declination. The inside is thus composed of 360° small squares which are divided off in azimuth by three dark squares alternately in each five now above and now below the central line. At the top is a representation of the Earth having its diurnal and seasonal motion, but with the center of the Earth always fixed. In the middle of this top is an eye-piece with a 45° mirror which enables the observer to see a pointer which because of the complicated mechanism traces out the position of the moon in its belt of mirrored and cross sectioned sky. Thus one is able to estimate its position to a fraction of a degree. So also we can see when this pointer points out on the earth the path of an eclipse, and we can note from the hands in the upper dial the year, month and day and on the lower dial the duration of the eclipse. There was an ingenious device now partly missing which showed the character of the eclipse, whether partial, total or annular. The eclipses of the moon occur when the pointer locates a small globe on the opposite side from the earth. This globe, of course has a slow forward and reverse motion. This face was the first one finished, and in many ways is the most remarkable.

The other face originally contaned satellite machines for Jupiter and Saturn, but were removed by Dr. Rittenhouse with the intention of bringing them up to date. This work, however, was never finished, and the parts, like the whole Orrery at Princeton are lost.

On June 18, 1767, he wrote Mr. Barton:

I hope you will persuade your Pequea friends to say for the clocks, till harvest is over; and then, I think, I may venture to promise them, for ready money: but at this time, one part of the Orrery is in such forwardness, that I am not willing to lay it b y till it is done. I hope it will far exceed the description I gave you of it. To-morrow morning I am to set off for Reading, at the request of the Commissioners of Berks county, who wrote to me about their town-clock. They had employed a * * * to make it, who, it seems, is not able to go through with it: if I should undertake to finish it, this will, likewise, retard the great work.

On November 17th, 1767, at the commencement, the College of Philadelphia, then in its meridian splendor, bestowed on David Rittenhouse, then present, the honorary degree of Master of Arts, Dr. William Smith, the Provost, addressing him as follows:

Sir,--The trustees of this College (the faculty of professors cheerfully concurring), being ever desirous to distinguish real merit, especially in the natives of this province,--and well-assured of the extraordinary progress and improvement which you have made, by a felicity of natural genius, in mechanics, mathematics, astronomy, and other liberal arts and sciences, all which you have adorned by singular modesty and irreproachable morals,--have authorized and required me to admit you to the honorary degree of Master of Arts, in this seminary: I do therefore, by virtue of this authority, most cheerfully admit, &c.

The erratic James Cannon received his bachelor's degree at the same time.

Towards the dose of April, 1770, the Orrery was purchased for the College of New Jersey. Dr. Witherspoon, the President, and a number of other interested gentlemen rode out to Norriton April 23rd, 1770, and placed in David Rittenhouse's hands three hundred pounds for the newly finished Orrery. As the trustees of the College had, through Dr. Smith, been in treaty with Rittenhouse, he was immediately conscious of some unpleasant censure from Philadelphia. He writes, February 4, 1770:

Dr. Smith, to whom I am indebted for many kindnesses, is very urgent to have me come to Philadelphia to reside, which it is probable I may do shortly: but I am not yet determined. If I live to write again, you shall know more of my mind: in the mean time, I shall be glad to have your opinion of the matter.

And on March 12th:

I would not, on any account, incur the imputation of cunning; nor, are there, probably, many persons living who deserve it less: yet I am greatly mistaken if this matter (his transfer of the Orrery to Princeton College) does not, in the end, turn out to my advantage, and consequently, to your satisfaction. At present, the point is settled as follows: I am to begin another (Orrery) immediately, and finish it expeditiously, for the College of Philadelphia. This I am not sorry for; since the making of a second will be but an amusement, compared with the first: And who knows, but that the rest of the colonies may catch the contagion.

The following newspaper article had appeared in the Pennsylvania Journal and Weekly Advertiser, April 26th, 1770:

It is with pleasure we inform the public that the Orrery of which the American Philosophical Society formerly published an account projected and executed by Mr. David Rittenhouse in this Province is now almost finished. As this is an American production and much more compleat than anything of the-kind ever made in Europe, it must give great pleasure to every lover of his country to see her rising to fame in the sublime science as well as every improvement in the arts. Dr. Witherspoon accompanied by some gentlemen went on Saturday last to see and converse with the ingenious artist, and being convinced of the superior advantages that must arise from this new invented Orrery in the study of natural philosophy, and desirous to encourage so truly great a genius, purchased it for the use of the College of New Jersey.

Dr. Smith, on February 5th, also wrote Mr. Barton:

I never met with greater mortification than to find Mr. Rittenhouse had, in my absence, made a sort of agreement to let his Orrery go to the Jersey College. I had constantly told him, that if the Assembly did not take it, I would take it for our College, and would have paid the full sum, should I have begged the money. I thought I could depend, as much as on any thing under the sun, that after Mr. Rittenhouse knew my intentions about it, he would not have listened to any proposal for disposing of it, without advising me, and giving our College the first opportunity to purchase. I think Mr. Rittenhouse was never so little himself, as to suffer himself to be taken off his guard on this occasion. This province is willing to honor him, as her own; and believe me, many of his friends wondered at the newspaper article; and regretted that he should think so little of his noble invention, as to consent to let it go to a village; unless he had first found, on trial, that his friends in this city had not spirit to take it: For if he would wish to be known by this work--and introduced to the best business and commissions for instruments, from all parts of the continent,--his Orrery being placed in our College, where so many strangers would have an opportunity of seeing it, was the sure way to be serviceable to Himself.

You will think, by all this, that I am offended with him, and that our friendship may hereby be interrupted: Far from it--I went to see him, the day the newspaper announced the affair. I soon found that I had little occasion to say any thing: he was convinced, before I saw him, that he had gone too far. But still, as no time was fixed for delivering the Orrery, I was glad to find he had concluded that it should not be delivered till next winter; against which time, he said, he could have a second one made, if this one staid with him for his hands to work by. As I love Mr. Rittenhouse, and would not give a man of such delicate feelings a moment's uneasiness, I agreed to wave the honour of having the first Orrery, and to take the second.

The result will be, I think, that he will keep his Orrery till towards winter; and should they not then receive it, in the Jersies, they will take it at New York.

On the seventh of the following month, Dr. Smith wrote Dr. Barton:

Your and my friend, Mr. Rittenhouse, will be with you on Saturday. The Governor says, the Orrery shall not go: he would rather pay for it, himself. He has ordered a meeting of the Trustees on Tuesday next; and declares it as his opinion, that we ought to have the first Orrery, and not the second,--even if the second should be the best.

And on March 22, 1771, Rev. Dr. Peters wrote Mr. Barton:

Dr. Smith has done wonders, in favour of our friend Rittenhouse. His zeal has been very active: he has got enough to pay him for a second orrery; and the assembly has given him 3001 [I assume this is a typo of £300]. The Doctor, in his introductory lecture, was honoured with the principal men of all denominations, who swallowed every word he said, with the pleasure that attends eating the choicest viands; and in the close, when he came to mention the orrery, he over-excelled his very self!--Your son will acquaint you with all the particulars respecting it. The lectures are crowded by such as think they can, thereby, be made capable of understanding that wonderful machine: whereas, after all, their eyes only will give them the truth, from the figures, and motions, and places, and magnitudes of the heavenly bodies.

A week before this last letter, on the 15th of March, Rittenhouse writes his brother-in-law:

Dr. Smith bids me to tell you he will write by your son William. He is fully employed, at present, with his Lectures, and has great success, having raised upwards of two hundred pounds. I am sure you would afford me some additional compassion, if you knew the drudgery of explaining the Orrery to two hundred persons, in small companies of ten or twelve, each: the satisfaction they universally express, makes however some amends.

On March 23, Dr. Smith writes the Rev. Mr. Barton:

I have been so busy these two months past, that I could not find a moment's leisure to write. A good deal of time was to be given to the public lectures, the Orrery, and the getting our dear friend Rittenhouse brought into as advantageous a light as possible, on his first entrance into this town as an inhabitant; all which has succeeded to our utmost wishes; and the notice taken of him by the province, is equally to his honour and theirs. The loss of his wife has greatly disconcerted him; but we try to keep up his spirits, under it.

The Rittenhouse Orrery is alluded to in "The Vision of Columbus", published at Hartford in 1787:

See the sage RITTENHOUSE, with ardent eye,
Lift the long tube and pierce the starry sky;
Clear in his view the circling systems roll,
And broader splendours-gild the central pole.
He marks what laws th'eccentric wand'rers bind,
Copies Creation in his forming mind,
And bids, beneath his hand, in-semblance rise,
With mimic orbs, the labours of the skies.
There wond'ring crouds with raptur'd eye behold
The spangled Heav'ns their mystic maze unfold;
While each glad sage his splendid Hall shall grace,
With all the spheres that cleave th'ethereal space.

Both Orreries are mentioned by American and foreign travelers passing through Philadelphia. John Adams, August 27, 1776, says of the Princeton Orrery:

Here we saw a most beautiful machine--an Orrery or planetarium constructed by Mr. Rittenhouse of Philadelphia. It exhibits almost every motion in the astronomical world.

Later, on the 14th of March, 1818, writing Thomas Jefferson, he says:

Rittenhouse was a virtuous and amiable man, an exquisite mechanician, master of the astronomy known in his time, an expert mathematician, a patient calculator of numbers.

The legislature of Pennsylvania, which had been exceedingly generous to the College, the American Philosophical Society, and arts and science in general, thus expressed their honorable testimony on the date of March 8, 1771:

The members of assembly, having viewed the Orrery constructed by Mr. David Rittenhouse, a native of this Province, and being of opinion that it greatly exceeds all others hitherto constructed, in demonstrating the true Situations of the celestial Bodies, their Magnitudes, Motions, Distances, Periods, Eclipses, and Order, upon the principles of the Newtonian System:

Resolved, That the sum of three hundred pounds be given to Mr. Rittenhouse, as a Testimony of the high sense which this House entertain of his Mathematical genius and Mechanical abilities, in constructing the said Orrery. And a certificate for the said sum, being drawn at the table, was signed by the Speaker and delivered to Mr. Evans.

Ordered, That Mr. Evans, Mr. Rhoads, Mr. James, Mr. Rodman, Mr. Morton, Mr. Carpenter, Mr. Montgomery, and Mr. Edwards, with the Speaker [Joseph Galloway], be a Committee to agree with and purchase from Mr. Rittenhouse a new Orrery, for the use of the Public, at any sum not exceeding four hundred pounds, lawful money of this Province.

The committee, named in the above order of the general assembly, made the following report to that body, on the 24th of September, 1771; viz.:

The committee appointed to agree with, and purchase from Mr. Rittenhouse a new Orrery for the use of the public, beg leave to report, that they have, in pursuance of the order of assembly, agreed with Mr. Rittenhouse for a new Orrery, at the price of four hundred pounds, the price limited by the house; to consist of one principal square (face,) of eight feet or more each way, with two wings; making in the whole one large front, as nearly resembling the form of the Orrery now standing in the College of the city of Philadelphia, as its superior size will admit.

The labors of Rittenhouse and Smith were deterred by war and other duties. Dr. Smith was pushed aside by the turn of politics, and spent the time of the British occupation on the Barbadoes Farm at Norriton, which the minutes of October 8th, 1784, confirm as a proposed site of the University at that time. The labors of Rittenhouse other than at the University are too varied to be discussed in a paper of this length. When the factions temporarily in control dispossessed the college November 27th, 1779, and renamed it The University of the State of Pennsylvania, John Ewing refused his election as Vice-Provost. At the same time David Rittenhouse, a Trustee because of his position of State Treasurer, was elected Professor of Astronomy, but on February 8, 1780, he was elected Vice-Provost and Professor at a combined salary Of £400 to teach geography, practical astronomy, and to divide natural and experimental philosophy with Dr. Ewing, who had previously been elected Provost. He was to receive also a fee Of 22s 6d from every graduate. Both Ewing's and Rittenhouse's trusteeships were vacated by their accepting these positions in the College. It is interesting to note that Thomas Paine, author of "Common Sense" and editor of "The Federal Orrery", received the first honorary degree of Master of Arts in the new University of the State of Pennsylvania.

On April 13, 1782, David Rittenhouse resigned his position at the University on account of added duties and larger fees in the treasurership, and was immediately elected Trustee again, taking the oath September 19th, 1782, and appearing at the board meeting on December 11th, 1782. But he was appropriately absent December 23rd, 1782, when a new seal was adopted, of which the following is the description given in the minutes:

The seal to be two inches in diameter, the device a front view of the Orrery belonging to the University, invented and made by David Rittenhouse, Esq., Above the Orrery a star of the first magnitude in full radiance, being one of the thirteen states in the arms of the United States representing the state of Pennsylvania. The inscription, Sigillium Universitatis Pennsylvaniensis.

The minutes continue:

Mr. Hopkinson requested to have the above engraved and to superintend the execution thereof, and that the Treasurer be directed to pay the expense attending the same. The old seal to be sold for what it will bring.

The College was restored March 6th, 1789, and on August 4th, 1790, David Rittenhouse resigned as trustee, of the University of the State of Pennsylvania, pleading his indisposition an presenting a very valuable timepiece which he has had put up in the Provost's room, and which his diary shows he had most carefully regulated. On November 4th, 1789, his nephew, David Evans had made a clock case for this timepiece at a cost of £11. This took the place of the one bought from Dr. Rittenhouse by Provost William Smith, and desired to be removed September 20th, 1780. This clock was probably the last one made by Rittenhouse's skilful hands.

The resignation was unanimously laid on the table, and when the College and the University were united by the Act of September 30th, 1791, (written, it is said, by Dr. Smith), he was one of the twelve trustees contributed by the University of the State of Pennsylvania, who with the twelve from the college formed the first body of twenty-four trustees of the University of Pennsylvania. But Franklin had died, and Provost Smith, it is said, missed the election by one vote, and in the course of the final settlements, between the University and Dr. Smith, who had been described by John Adams in 1776 as "soft, polite, insinuating, adulating, sensible, learned, industrious and indefatigable" the following letter was written Chairman Charles Pettit of the Committee of the Board of Trustees, and explains the payments made for the Orrery. It is also to be remembered that, shortly before, Dr. Smith had lost his wife, and David Rittenhouse his son-in-law in the most terrible pestilence that has ever visited Philadelphia.

Decem. 26th, 1793.


Dr. Smith being very desirous of purchasing the Orrery for the College of Philadelphia, undertook to raise money in his own way to pay for it. He procured several companies of 8 or 10 persons each to subscribe £5. I think, each Comp. They were to attend Lectures which I was to give on the Orrery. All the money so collected was I believe paid to me. How far it is right for the Dr. to have credit for this money, when so much of the drudgery of raising it fell upon me, I will not determine. I need not add that nothing is farther from my thoughts than to put in any claim. But Dr. Smith says, and I believe it to be a true state of the case, that he himself gave a course of Lectures in Natural Philosophy, during the same winter, and that the money raised by them was also applied towards paying for the Orrery. The whole sum I received was what Dr. Smith reports. £65 of which was in his presence, and as soon as it came into my hands paid to Parnell Gibbs and John Folwell, Joiners, for the Orrery Case. So that the remainder or £42.10 was all that I have ever received for my labour.

I am, Sir, your humble Servant

Davd Rittenhouse.

Mr. Pettit.

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