While working at James Logan's estate,
Stenton, Godfrey observed a reflection in a piece of broken glass which prompted the idea for the reflecting quadrant. Godfrey accessed a copy of
Isaac Newton's
Philosophiæ Naturalis Principia Mathematica in Logan's library to further expand his idea. While challenged by the Latin text, with Logan's support, he was able to learn Latin and apply Newton's theories to his idea. Godfrey began experiments to develop an improved
quadrant for determining
latitude for navigation. He carried out much of his work in part of a home he rented from
Benjamin Franklin. James Logan sent a description of Godfrey's invention to
Edmond Halley, the
Astronomer Royal in Britain. Logan was surprised to then see an almost identical device described as invented by
John Hadley in the
Philosophical Transactions of the Royal Society. Hadley received a patent for the octant in 1734 without contest. Godfrey, along with Logan, wrote to the Royal Society to defend his claim that the device was his original invention. The communication including sworn affidavits signed by the Mayor of Philadelphia that Godfrey's octant was crafted by
Edmund Woolley of wood on November 1730. The communication also noted that Hadley's nephew was present at an early demonstration of his invention. His claim was denied, but he did receive a cash reward for his work from the Society. From 1729 to 1736, Godfrey worked as a publisher of almanacs. He also contributed essays on mathematics, astronomy and general topics to the
Pennsylvania Gazette and
Pennsylvania Journal. He assisted
Lewis Evans in conducting astronomical observations to correct the longitude of Philadelphia on maps published by Evans. which was the precursor of the
American Philosophical Society. Godfrey died in 1749 at the age of 45. He was originally interred at his farm near Germantown, but over time the grave fell into disrepair. In 1838,
John Fanning Watson reinterred the remains of Godfrey, his wife, father and mother to
Laurel Hill Cemetery. In 1843, a memorial erected by the
Mercantile Library Company of Philadelphia was placed atop their graves. ==Personal life==