we know that leonardo sent a letter to the duke of milan, ludovico sforza, also know as "il moro" becauseof his swarthy complexion. the duke presided over the liveliest court in europe. his province of lombardy was then, as it still is today, the wealthiest province in italy. to gain his new position at court, leonardo recommended himself primarily as a military engineer. "i can supply," leonardo wrote, "an infinite number of engines of attack and defense." of the ten paragraphs in his letter, it is only in the last one that leonardo informs the duke, "that i can do as well as any other man as a painter." he also offers to undertake the creation of an equestrian statue to the duke's father, francesco sforza. to be out of favor at the court of lorenzo de' medici was the worst misfortune that could befall a florentine artist, and leonardo was not a court favorite. his interest in the natural sciences was puzzling to the court. this drawing probably suggests something of his mental conflict. it is a sketch for the adoration, but in the corner there is a design for a hydrometer, a device for

ludovico sforza, a man of his time and bject to its violence and ruthlessness, was nonetheless an astuteand conscientious ruler. leonardo provided a fertile source of ideas for the duke. many of leonardo's drawings relate to water power because that was the principal source of energy in that region. we find designs for the building of sluices and canals and a movable bridge... paddlewheels for water transportation... pulleys for mechanical leverage to circumvent the inherent limits of man's physical strength. he discovered laws of light refraction. he noted that an image passing through one globe of water, representing the eye, would appear upside down. yet the same image passed through a second globe would again be inverted and appear right side up. [seagulls calling] among the most celebrated of leonardo's scientific investigations was to ascertain the nature of flight and to envisage the possibility of human flight. over a period of 30 years, he produced scores of drawings and thousands of words on the subject. he designed a parachute and an air screw, which we now call a helicopter.