In the year 1704 there was born on a farm on the outskirts of Germantown, Pennsylvania, a boy who was destined to become one of the most interesting personages in the colonial history of this country. His father, a maltster by trade, died when Thomas Godfrey, for that was his name, was but a year old. His mother soon married again, and at the age of twelve Thomas was apprenticed to a glazier of Philadelphia with whom he learned his trade. He became a good craftsman and we find him in 1728 at the age of 24 working at his trade at “Stenton,” the home of James Logan who was the most influential man of the colony in his time.
James Logan, a member of the Society of Friends, had come to the colony as William Penn’s secretary and had held such offices as Chief Justice and Acting Governor. Highly educated, a scientist of no mean ability, he numbered among his friends the leading scientists of his day at home and abroad. As a patron of the arts and sciences, he was unfailing in assistance to searchers in those fields who sought his aid.
Imagine Mr. Logan’s surprise when the glazier, Thomas Godfrey, approached him with a request to borrow the then lately published Newton’s Principia. Questioning him with interest that a glazier should desire a scientific work in Latin, he found to his utter astonishment that Godfrey, although of scanty formal schooling, had through self-instruction attained a profound knowledge of mathematics and astronomy with sufficient Latin to pursue the more advanced treatises then written in that language. As kindred spirits with
a common interest, these two formed a friendship that was strongly to influence the scientific adventures on which Godfrey was shortly to embark.
Becoming interested in navigation, Godfrey took up the problem of improving the form of backstaff then in use called the Davis’ Quadrant (Fig. 1), whose faults were legion. In the spring of 1730 he completed a design of backstaff which he called the Mariner’s Bow (Fig. 2). He then set to work to design an instrument to determine a star’s altitude as an improvement of the forestaff. He first considered one reflection to bring the star to the horizon, but the least motion caused the objects to fly apart. He then examined what two reflections of the star would do and found that it solved the problem perfectly. He found that the angular distance between the two objects was double the inclination of the reflecting planes, thus discovering the principle of the modern sextant. This he disclosed to Mr. Logan late in May or early in June of that year.
Meeting George Steward, mate of the sloop Trueman, in October, 1730, he invested him in his invention and obtained is seagoing Davis’ Quadrant to be used as a test instrument. Godfrey took the quadrant to a carpenter named Edmund Woolley in accordance with drawings furnished by the inventor made a contrivance that slipped over the end of the main beam in place of the horizon vane, thus making a reflecting instrument with a limb of 30 degrees of arc (Fig. 3). Using the original scale on the 30 Arch, it was necessary to double the readings to obtain the correct angles of observation. Provision was made for revolving the index mirror through 20 degrees or more from the zero position when angles of greater than 60 degrees were to be taken. Subsequent readings in this case were increased by the angle of rotation of the index mirror and the sum doubled to obtain the observed angle.
This quadrant with attachments was shown to James Logan in November, 1730, and he had Joshua Fisher, who was then surveying Delaware Bay, give it a trial, which he did with most satisfactory results.
The instrument was then given a sea test. The mate, George Steward of the sloop Trueman, John Cox master, took his modified quadrant on a cruise to the West Indies, departing from Philadelphia November 28, 1730, and returning February 19, 1731. Several observations of the sun, stars, and lunar distances were taken by the master and the mate using the modified instrument and another quadrant for simultaneous observations. They “found these of Mr. Godfrey’s instrument as far as they could judge very exact.”
The Godfrey Reflecting Quadrant had now proved itself. The inventor being unknown abroad, James Logan planned to interest his friends and the Royal Society in London in the invention, hoping to secure suitable recognition and reward for the inventor. However, affairs of importance prevented him from writing until May 25, 1732, a year later. He then wrote his friend Dr. Halley, the Astronomer Royal and Fellow of the Royal Society, from whom, according to an understanding made when Logan was in London in 1724, he had reason to expect quick and sympathetic action. A model of the Reflecting Quadrant (Fig. 4) accompanied the letter which gave a description of the instrument, the date of its inception, a history of the inventor, and a plea for consideration of his adequate reward.
The letter was delivered but no answer was ever forthcoming. Subsequently it was discovered that John Hadley, Vice-President of the Royal Society, had presented to the Society two types of reflecting instruments which he called Octants (Figs. 5 & 6). This was printed in the Philosophical Transactions under the date of May 13, 1731, which antedated James Logan’s letter by over a year. However, the date of inception was the deciding fact to establish as to priority of invention.
Hearing nothing from the first letter, it was decided to send another communication to the Society which was done on December 4, 1733. This time the matter was to be presented to Dr. Peter Collinson, an eminent botanist and Fellow of the Royal Society. The communication contained a copy of James Logan’s first letter, a letter by Thomas Godfrey presenting his Manner's Bow to the Society, and certain depositions relative to the invention of the Reflecting Quadrant (presumably those of John Cox, George Steward, and Edmund Woolley, copies of which are appended) - Captain Wright in the employ of the Colony was commissioned to present these papers and represent the interests of the inventor. In a letter of February 4, 1734, he writes Mr. Logan the results of his efforts, here quoted in part:
. . . Mr. Norris and myself were introduced [at a meeting of the Royal Society] by Mr. Collinson; and upon reading the description of the Bow, I had the pleasure of hearing your first letter to Dr. Halley read; which was all that was read; and when done Mr. Machen addressed the President . . . and said he had vouchers ready on the table for any one’s perusal, who might doubt the truth of that letter [Mr. Logan’s first letter], or the instrument being genuine, and no ways taken from Hadley’s, but found out about the same time at his was, or rather prior to it, if the vouchers were true; and if they were not, then, said he, we must believe all the people of Pennsylvania are combined to impose on this Society,—which no reasonable man can do.” He said some shrewed things of Dr. Halley and concluded with saying that “the inventor claimed the justice of having at description registered, which he thought no one could deny him; and should that instrument be the park for the longitude, the inventors of the rest must dispute their priority before the learned in law.” No person said anything against it, so that it will be registered.
Upon receipt of the Captain’s letter, prospects seemed more cheerful for Godfrey’s cause; but the winter passed without anything tangible happening. In order to keep the subject of the Reflecting Quadrant alive, Mr. Logan wrote a final letter to the Royal Society on June 28, 1734, further explaining the Mariner’s Bow. In its concluding words, he again referred to the Reflecting Quadrant in part as follows:
In the same year 1730, after he [Thomas Godfrey] was satisfied in this [the invention of the Bow], he applied himself to think of the reflecting instrument by speculums for help in case of longitude, tho ’tis also useful in taking latitudes; and one of these has been abundantly proven by the maker, and those who had it with them, when taken to sea, and there used in observing the latitude the winter of that year and brought back again to Philadelphia before the end of February 1731, and was in my keeping some months immediately after. It was indeed unhappy that having in my power, seeing that he had no acquaintance nor knowledge of persons in England, that I transmitted not an account of it sooner. But I had other affairs of more importance to me; and it was owing to an accident which gave me some uneasiness viz. his attempting to publish some account of it in print here, that I transmitted it at last in May 1732 to Dr. Halley, to whom I made no doubt but the invention would appear entirely new; and I must own, I could not but wonder that our good will at least was never acknowledged. This, on my part, was all the merit I had to claim. ... I only wish that the ingenious inventor himself might by some means be taken notice of, in a manner that might be of real advantage to him ....
This letter received recognition by the Society, in that parts of it referring to the Mariner’s Bow were printed in the Philosophical Transactions for the year 1734. With this feeble recognition of the demonstrated ability of Thomas Godfrey, the Royal Society was finished with him. Hadley seems to have received all the glory and profit of the invention, the octant being sold for years under his name. His position as Vice-President of the Royal Society and as a scientist of really great and deserved fame for his improvement of the reflecting telescope and other scientific achievements made his claim to the principle of the octant difficult to assail; certainly Godfery was in no financial position to contest it by law.
Certain authorities claim that Hadley’s invention was made in the summer of 1730 and Godfrey’s in October of that year. James Logan places the date of inception of the Godfrey invention as about the last of May or the first of June, 1730. This gives Godfrey the priority. However, strange as it may seem, the claim of original invention must go to Sir Isaac Newton, a claim antedating those of Hadley and Godfrey by fifteen years at least, although they must be credited with the reinvention of a temporarily lost idea.
When Dr. Halley died in 1742, there was found among his papers in the handwriting of Sir Isaac Newton the description and sketch of a reflecting instrument for observing “the Moon’s Distance to Fixt Stars” and also altitudes of heavenly bodies (Fig. 7). This instrument uses the principle of double reflection. Sir John Hirschel says in his Treatise on Astronomy that Dr. Halley had suppressed Newton’s invention. It may be a coincidence that a similar thing happened to Godfrey, but unfortunately disclosure did not bring him justice.
There have been numerous accounts of Thomas Godfrey describing him as a self-taught American mathematician, a man of intemperate habits, a humble artisan in Philadelphia who was rewarded for his invention by the Royal Society with a gift of 200 pounds sterling in value in furniture rather than money because of his intemperance.
As far as can be determined, Godfrey was never rewarded by the Royal Society, but of course he may have received presents from some admirers among its members which could have been misconstrued by outsiders as a gift from the Society itself.
Of course intemperate drinking was not unusual in that day, but it is doubtful if James Logan would have befriended Godfrey were he a drunkard. Benjamin Franklin, who cared little for Godfrey and who gossiped about such things, never mentioned him as a drinker but as a poor business man who “worked little, being always absorbed in his mathematics.” Furthermore Godfrey was one of the directors of Franklin’s circulating library about this lime, and among his other activities composed and published The Pennsylvania Almanac for the years 1733 and 1734. It is difficult to believe in this period that he could justly have been called intemperate. Later when disillusioned by the injustice of his gods, mathematics, and science, he may have been all that was claimed of him.
The year 1734 is the last recorded of his life until the end. At his death the Pennsylvania Gazette of December 19, 1749, carried the following notice:
Philadelphia December 19
Last week died here Mr. Thomas Godfrey, who had an uncommon Genius for all kinds of Mathematical Learning, with which he was extremely well acquainted. He invented the New Reflecting Quadrant used in Navigation.
He had lived his last years in reduced circumstances and was buried in the family burying ground on the old farm.
In Philadelphia, in Laurel Hill Cemetery, is a monument erected to Thomas Godfrey by his admirers in 1843, marking his present grave; and there one may doff his cap to the American inventor of the Reflecting Quadrant, the Model “T” of the 1940 sextant.