SCIENTIFIC CAREER
One of Wren's friends, another great scientist and architect and a fellow Westminster Schoolboy, Robert Hooke said of him  "Since the time of Archimedes there scarce ever met in one man in so great perfection such a mechanical hand and so philosophical mind."

When a fellow of All Souls, Wren constructed a transparent beehive for scientific observation; he began observing the moon,  which was to lead to the invention of micrometers for the telescope. He experimented on terrestrial magnetism and had taken  part in medical experiments while at Wadham College, performing the first successful injection of a substance into the  bloodstream (of a dog).

In Gresham College, he did experiments involving determining longitude through magnetic variation and through lunar  observation to help with navigation, and helped construct a 35-foot (11 m) telescope with Sir Paul Neile. Wren also studied  and improved the microscope and telescope at this time. He had also been making observations of the planet Saturn from around  1652 with the aim of explaining its appearance. His hypothesis was written up in De corpore saturni but before the work was  published, Huygens presented his theory of the rings of Saturn. Immediately Wren recognised this as a better hypothesis than  his own and De corpore saturni was never published. In addition, he constructed an exquisitely detailed lunar model and  presented it to the king. Also his contribution to mathematics should be noted; in 1658, he found the length of an arc of the  cycloid using an exhaustion proof based on dissections to reduce the problem to summing segments of chords of a circle which  are in geometric progression.

A year into Wren's appointment as a Savilian Professor in Oxford, the Royal Society was created and Wren became an active  member. As Savilian Professor, Wren studied mechanics thoroughly, especially elastic collisions and pendulum motions. He also  directed his far-ranging intelligence to the study of meteorology: in 1662 he invented the tipping bucket rain gauge and, in  1663, designed a "weather-clock" that would record temperature, humidity, rainfall and barometric pressure. A working weather  clock based on Wren's design was completed by Robert Hooke in 1679.

In addition, Wren experimented on muscle functionality, hypothesizing that the swelling and shrinking of muscles might proceed  from a fermentative motion arising from the mixture of two heterogeneous fluids. Although this is incorrect, it was at least  founded upon observation and may mark a new outlook on medicine: specialisation.

Another topic to which Wren contributed was optics. He published a description of an engine to create perspective drawings and  he discussed the grinding of conical lenses and mirrors. Out of this work came another of Wren's important mathematical  results, namely that the hyperboloid of revolution is a ruled surface. These results were published in 1669. In subsequent  years, Wren continued with his work with the Royal Society, although after the 1680s his scientific interests seem to have  waned: no doubt his architectural and official duties absorbed more time.

It was a problem posed by Wren that serves as an ultimate source to the conception of Newton's Principia Mathematica  Philosophiae Naturalis. Robert Hooke had theorised that planets, moving in vacuo, describe orbits around the Sun because of a  rectilinear inertial motion by the tangent and an accelerated motion towards the Sun. Wren's challenge to Halley and Hooke,  for the reward of a book worth thirty shillings, was to provide, within the context of Hooke's hypothesis, a mathematical  theory linking the Kepler's laws with a specific force law. Halley took the problem to Newton for advice, prompting the latter  to write a nine page answer, De motu corporum in gyrum, which was later to be expanded into the Principia.

Mentioned above are only a few of Wren's scientific works. He also studied other areas, ranging from agriculture, ballistics,  water and freezing, light and refraction, to name only a few. Thomas Birch's History of the Royal Society is one of the most  important sources of our knowledge not only of the origins of the Society, but also the day to day running of the Society. It  is in these records that most of Wren's known scientific works are recorded.