1667 in science

The year 1667 in science and technology involved some significant events.

Astronomy

Johann Joachim Becher originates what will become known as phlogiston theory in his Physical Education.{{cite book|last=Bowler|first=Peter J.|title=Making modern science: A historical survey|url=https://books.google.com/books?id=-V9jM4FkUacC|year=2005|publisher=University of Chicago Press|page=60|isbn=9780226068602}}

Thomas Sprat publishes [https://archive.org/details/bub_gb_g30OAAAAQAAJ The History of the Royal-Society of London, for the Improving of Natural Knowledge].

James Gregory demonstrates the transcendence of π.{{cite book|first=Matthew|last=Richardson|title=The Penguin Book of Firsts|year=2001|publisher=Penguin Books India|location=New Delhi|isbn=0-14-302771-9|page=184}}

June 15 – Jean-Baptiste Denys performs the first blood transfusion from a lamb into a boy.
Robert Hooke demonstrates that the alteration of the blood in the lungs is essential for respiration.
Thomas Willis publishes Pathologicae Cerebri, et nervosi generis specimen.

Nicolas Steno publishes Elementorum Myologiae Specimen, seu Musculi Descriptio Geometrica. Cui accedunt canis carchariae dissectum caput, et dissectus piscis ex canum genere in Florence, providing a foundation for the study of muscle mechanics, the ovary (based on his dissection of dogfish), and the sedimentary theory of geology.{{cite book|title=Nicolaus Steno (Niels Stensen) and Erasmus Bartholinus: two 17th century Danish scientists and the foundation of exact geology and crystallography|first=Axel|last=Garboe|location=Copenhagen|publisher=Reitzel|year=1954}}

April 3 – Edward Somerset, 2nd Marquess of Worcester, English inventor (born 1601?)
April 10 – Jan Marek Marci, Bohemian physician (born 1595)
June 5 – Grégoire de Saint-Vincent, Flemish mathematician (born 1584)
probable date – Peter Mundy, English traveller (born c. 1596)