Summary
The following summaries are from the codex whose English translation was prepared by Culturando and Smithsonian Institution. Front Page The front page is titled "On Casting Medals". The first paragraph gives a brief recipe that consists of "emery", "nitric acid", "iron filings", "vinegar", "ashes of walnut leaves", and "finely ground straw ash". The second paragraph tells of the process of crushing diamonds into diamond powder and separating the powder from lead. The last paragraph explains how to crush large crystals into smaller crystals, and how to grind, purify, and color enamel. Folio 1 The first page in the folio one contains 11 diagrams with captions for each that relate to gravity, density, balance, and oscillations. The next page contains four diagrams and a lengthy paragraph on velocity and the differences in movement along the arc and chord of part of a circle. Leonardo comments on how gravity, which is caused by the "attraction of one object to another", takes place when an object is placed above another object and the top object is heavier than the bottom object. He also writes on the workings of a balance by describing how "the vertical center of a balance must always be perpendicular" and how the length of the arm on the balance is proportional to the amount of oscillations and the oscillation angle. A short commentary is included on relating density to weight, and he questions why ice floats in water if it is the denser of the two. In the first paragraph, Leonardo restates his theory on gravity and expands on it to say that the motion caused by gravity acts in the direction of the imaginary line between the two object's centers. He goes on to say that motion due to gravity is only caused because the objects have no way to resist gravity. Leonardo begins folio 3 with a declaration stating the science of machines is the most useful science overall because of its use by any moving object. Leonardo writes a lengthy amount of text about two weights that each weigh three pounds that are connected together on either side of a balance. The slopes that each object rests on are at different angles, however. Leonardo goes on to write that, because of the slopes, one weight may weigh three pounds, but it is only providing two pounds of force. The other weight, also three pounds, is similarly stated to only provide one pound of force because it is resting on a smaller incline. Later on this page, he writes on the forces a balance experiences depending on the location of weights on the balance. The first reference to pressure for this codex is made towards the end of this folio, relating it to the working of a balance. Leonardo starts off folio 5 by stating that if a man were to be in a flying machine, nothing should get in his way from the waist up, so that he can balance himself as one does in a boat. He goes on to write on how a bird's direction will change with the direction of the wind. A bird which is going in a straight line that comes into a cross breeze at a perpendicular angle will now be heading in a direction that is in between the two endpoints of each direction. He ends the first page by explaining that if a bird in a descent wants to turn left or right, then it will lower the wing on the side of the direction it wants to turn. Leonardo starts off by describing how a bird ascends or descends in different wind conditions. Here is a summary. He states that the only way for a bird to ascend when in a tailwind is for the bird, at its peak ascent, to turn in a semicircle and face the wind to continue its ascension in the opposite direction. Leonardo starts writing on a flying machine and comparing it with the notes he has already taken on the flight of birds. He states that "the bird" (machine) must attain a high altitude it case it were to turn over so as to have enough time to right itself. He notes that the framework needs to be strong with leather laces and raw silk for the ribs. He also adds that there should not be any metal in the machine because of its tendency to wear or break under stress. Leonardo goes on to write that if the "bird" is above the wind but turning into the wind, the "bird" must lower its tail otherwise it will overturn. He states that the action of lowering the tail to be less susceptible to wind in this situation will make it impossible for the "bird" to be overturned. He goes on to prove this by referencing the "Elements of Machinery". Afterwards, he writes on the compression of air due to the wings, and he states that the entire length of the wing is not used in the compression of air in front of the wing. To prove this, he asks readers to examine bird wings for themselves and to check the larger spacing in between the not as large feathers. It particularly looks at the effect of wind on the movement of a bird. Folio 10 Discusses the wings of a bird. Folio 11 Discussion of the importance of truth Folio 12 Folio 13 Folio 14 Folio 15 Folio 16 Folio 17 Folio 18 Back Page == Display in the U.S. ==