On February 5 “Dr. Wren was desired to think of an easy way for a universal measure different from that of a pendulum.” This was a question of devising an absolute standard of length dependent upon some natural phenomenon, which finally found expression in the metre and again in a standard of length derived by physicists from the wave-length of light. On February 12 “Dr. Wren proposed blacklead as a better means than oil for preserving the pivots of the wheels of watches and clocks from grating or wearing out.” On March 5 “the amanuensis was ordered to attend Dr. Wren to take directions concerning the experiment of water in the long tube.” This means the setting up of a water barometer, with water in place of the mercury of Torricelli’s experiment. On September 3, 1662, it is recorded that “it was referred to Dr. Wren to take care of making the several experiments mentioned at the last meetings concerning the _aquæ salientes_,” by which we are to understand the earliest experiments on the rise of liquids in capillary tubes. The record goes on to say, “The request of the Society made at the last meeting to Dr. Wren about comparing the Earl of Sandwich’s experiments was continued but it being a business of difficulty and much calculation required more time than he could yet obtain from his other employments.” None the less, a week later “Dr. Wren was reminded of promoting Mr. Rooke’s observations concerning motions of the satellites of Jupiter,” and a fortnight later still, “Dr. Wren presented some cuts done by himself in a new way of etching whereby he said he could almost as soon do a piece on a plate of glass as another could draw it with a crayon on paper.” At the same meeting, too, “Dr. Wren proposed the experiment of forcing up water in different pieces of different diameter and different altitudes ... and was desired to bring a description of this experiment at the next meeting....” On October 8 of the same year “Dr. Wren offered an experiment about the undulation of quicksilver in a crooked tube which he suggested was for the velocity of it proportional to the vibration of a pendulum. He was desired to prosecute the experiment and to give in an account of it.” Sprat, in his _History of the Royal Society_, lays especial stress on a scheme of work devised by Wren in the interests of agriculture. “The second work (the first was the Doctrine of Motion) which he has advanced, is the History of Seasons; which will be of admirable benefit to mankind, if it shall be constantly pursued, and derived down to posterity. His proposal therefore was, to comprehend a diary of wind, weather, and other conditions of the air, as to heat, cold, and weight; and also a general description of the year, whether contagious or healthful to men or beasts; with an account of epidemical diseases, of blasts, mildews, and other accidents, belonging to grain, cattle, fish, fowl, and insects.”