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In [ 75 Scientific Method], as seen in the screenshot below, there is a paddle being part of Leonardo's design for a paddleboat. Leonardo drew several designs for various kinds of watercraft, and one of his interests was in harnessing water as a force of energy or, as with his plans to try and divert or dam watercourses, to provide and control a water supply for instance for the city of Florence which was landlocked. |  |
[75 Scientific Method]
 | The paddle seen, though seen indistinctly, in the above screenshot relates most closely, given the lack in the screenshot of any other part of the boat, to the paddleboat design in the Codex Atlanticus, folio 945 r., which is located in the Biblioteca Ambrosiana in Milan. The drawings on that folio, dateable to 1482 according to www.museoscienza.org and 1487-89 according to the book "Leonardo's Machines", illustrate a boat with a paddle-wheel, with the hull only partly drawn and some details. Despite the unfinished hull, several components are highlighted:, namely the supporting deck for the advance mechanism and for the belt transmission with the large spider spool. There are a few annotations on this folio which refer to other subjects. |
In manuscripts by engineers contemporary with Leonardo, the designs for paddleboats are generally presented in their final form without an indication of the research process behind them. Leonardo's drawings, however, are disordered but almost every new invention of design modification that he made for one or other of his mechanisms are in the visual notes.
The navigation of rivers and canals poses different problems than sea navigation does. Once the flotation problem was worked out, the boat required a propulsion system, and Leonardo designed a boat which could easily navigate using a system more practicable than oars. Oars need to be moved using a repetitive action producing discontinuous energy. With paddles, however, the operators use their feet (or, in other models, their arms) to move the large side wheels, making the craft move without interruption. Therefore, in the centre of the boat there is a pedal mechanism for propelling the boat, a vital technical device. The idea was, by substituting oars with wheels, to use a working principle opposite to that employed in mills - not the action of the water moving a wheel but rather the manual actionof the paddle on the wheel in the water making the vessel move. That is, by and large, the principle behind modern paddleboats.
Leonardo's drawing is dateable somewhere between 1482-89 if we accept the broadest possible dating. A series of elements suggest the period to be 1487-89 namely the Lombard names on the reverse of the folio in handwriting which is not Leonardo's, together with a list of words which, when they appear in, say, the Codex Trivulzianus, signify that the Maestro was learning Latin so that, not having had a university education, he could access the era's cultural sources which, not just the texts of the ancient Romans, were in Latin. At that time, the Maestro was in Milan, having just moved there recently from Florence. Cities such as Milan and Florence did not always have a link by water to the sea which they could be certain of wholly controlling themselves, which was a deeply felt limitation in a period of history when travel by sea and, where navigable, river was the fastest and the most effective means of communication, not to mention the transport of goods and access to a water supply. Milan, Florence and other such cities used their political and economic power to strive to overcome the problem. Where there was also a limited water supply or one that was in the main or even partial control of other States, that too was a motive behind many of the political and even military maneuverings of the time, for instance Milan's expansionist ambitions toward the Ligurian coast and for instance the war constantly waged by Florence against Pisa (located further along the River Arno nearer the sea). Research in the field of hydraulic engineering was slanted toward benefitting such city employers, and the rewards given for advances made in the field were high.
above: Map excerpt. Click for complete map of Renaissance Italy
 | Therefore, the design of new types of vessels greatly occupied the minds of Renaissance engineers, especially with regard to ever-increasing commercial and wartime demands. Leonardo was not the first to design a vessel moved by paddle-wheels, as that had been dealt with by previous engineers including Taccola and Francesco di Giorgio. However, Leonardo made notable improvements to the paddle-moving mechanisms and offered a new way to approach the problem. |
The paddleboat was meant to be operated as follows:
- One or more men on the boat begin by pushing the left pedal. This pulls a belt which makes the centre mechanism rotate.
- Worked by the belt, the centre mechanism rotates clockwise, transmitting its movement to the inner right ring on the motor block. Two inner springs turn clockwirse engaging and meshing the outer toothed ring.
- The outer ring transmits the rotary motion to the upper gear which begins to rotate in a counter-clockwise direction. The motion is then transmitted to the right support axle, moving the paddle-wheel which rotates counter-clockwise. After this sequence the right pedal is pushed and the process continues in alternation.
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