=A.D. 1675.=--Picard (Jean), eminent astronomer, who succeeded Gassendi (A.D. 1632) as professor of astronomy at the Collège de France, is the first to observe electric light _in vacuo_. According to Tyndall (“Lessons in Electricity,” p. 88) it was while carrying a barometer from the Observatory to the Porte Saint-Michel in Paris that he noticed light in the vacuous portion. Sebastien and Cassini observed it afterwards in other barometers (see Tyndall’s “Lecture V.” p. 91, for Priestley’s description of the electric light _in vacuo_). It was this same scientist who had already given, in his “Mesure de la Terre,” 1671, Article IV, the description of the measurement of a degree of latitude made with instruments of his own manufacture. REFERENCES.--Humboldt, “Cosmos,” 1859, Vol. V. pp. 23, 24; Larousse, “Dict.,” Vol. XII. p. 937; “Phil. Hist. and Mem. of the Roy. Acad. at Paris,” London, 1742, Vol. I. pp. 208–221. =A.D. 1675.=--Newton (Sir Isaac), prominent English mathematician and natural philosopher, of whom Macaulay says that “in no other mind have the demonstrative faculty and the inductive faculty coexisted in such supreme excellence and perfect harmony,” communicates to the Royal Society his discovery that excited glass will attract any light bodies even to the surface opposite to that upon which it has been rubbed. This was successfully demonstrated by the Society, January 31, 1676. He improved the electric machine by substituting a glass globe for the globe of sulphur made use of by both Von Guericke and Boyle, the rubbers in every case being the hands of the operator. He appears to have somewhat anticipated Franklin’s great discovery, judging by the following letter he addressed, December 15, 1716, to the Rev. Dr. Law, in Suffolk: “Dear Doctor,” it begins, “He that in ye mine of knowledge deepest diggeth, hath, like every other miner ye least breathing time, and must sometimes at least come to terr; alt (terra alta) for air. In one of these respiratory intervals I now sit doune to write to you, my friend. You ask me how, with so much study, I manage to retene my health. Ah, my dear doctor, you have a better opinion of your lazy friend than he hath himself. Morpheus is my best companion; without eight or nine hours of him ye correspondent is not worth one Scavenger’s peruke. My practizes did at ye first hurt my stomach, but now I eat heartily enow, as y’ will see when I come down beside you. I have been much amused by ye singular φενομενα resulting from bringing a needle into contact with a piece of amber or resin fricated on silke clothe. Ye flame putteth me in mind of sheet lightning on a small--how very small--scale. But I shall in my epistles abjure philosophy, whereof when I come down to Sakly I’ll give you enow. I begin to scrawl at five mins. from nine of ye clk, and have in writing consumed ten mins. My Lord Somerset is announced.”