Quod erat demonstrandum.

Proved by Lagrange in Réflexions sur la résolution algébrique des équations in 1771.

Jacob Steiner - Vorlesungen über syntetische geometrie.

Gauss’s sphere.

René Descartes - La Géométrie. 

Christian Huygens - Choses à corriger aux pendules de mer. 1668.

Proposition XX.

Euclid - The Elements of Geometry, Book I

Proposition I. Problem.

To describe an equilateral triangle upon a given finite straight line. 

John Wallis - De Cycloide et Corporibus.

Pars prior. Fig 1. 

Pharynx with blocked trachea

You can see in this case, that the epiglottis failed to cover the trachea while this person was swallowing, and as a result, the meat lodged within the airway.

The epiglottis is elastic cartilage, and is a fairy stiff structure. Just like every other thing ingested, foods like meats (which are dense and generally not easily broken apart, even after chewing) can end up getting into the trachea if the epiglottis does not function correctly. However, it’s noted in this book that they can be more difficult to dislodge than other foods of comparable size, simply because they’re able to get “caught” on the epiglottis. An emergency tracheotomy is generally the only hope those patients have, as forceps or other medical tools are needed to dislodge the meat, and most people don’t carry those around in their pockets…

A Text-Book of Pathology. W. G. MacCallum, 1916.

(Fonte: biomedicalephemera, via scientificillustration)

Pentremite fossil and reconstruction

(Fonte: ulleung-desire, via scientificillustration)

Arteries and veins of the adult body.

Wonders of the Human Body. A. Le Pileur, 1871.

(Fonte: biomedicalephemera, via scientificillustration)

Mars.

(Fonte: bradsimantel, via scientificillustration)

Astronomische Zeichnungen, c. 1508

(via proustitute)

Dragon Curve

(Fonte: snortingpixiedust, via neonpi)

Snowflake #11 by Wægen

(Fonte: mincraeft, via neonpi)

Astronomy: a comet in the night sky. Wood engraving, n.d. [c.1860?].

(Fonte: serpentskirt, via scientificillustration)