120 Mr. Edward McOurdy [March 19, 



" How by moans of a certain machine many people may stay some 

 time under water. How and why I do not describe my method of 

 remaining - under water, or how long I can remain without eating : 

 and I do not publish or divulge this because of the evil nature of men 

 who would use them as means of destruction at the bottom of the 

 sea by smashing the ships in the keel and sinking them together 

 with the men in them. But I will impart others which are not 

 dangerous, because the mouth of the tube by which you breathe 

 appears above the water supported on leather bottles or corks." 



In connection with this passage reference may be made to one 

 in MS. B of the Paris MSS. entitled, " A way of escaping in a 

 tempest or shipwreck at sea," in which he tells how to construct a 

 coat of leather of double thickness which will be capable of being 

 inflated when necessary, and thus of serving as a life-saving jacket in 

 case of emergency. 



Senators Luca Beltrami associates the former of these passages 



with the Turkish war. Leonardo, as a reference in his manuscript 



shows, had been employed in the construction of a movable dam 



which should enable the line of the Isonzo to be flooded in the 



defence of the Yeneto against the Turkish invasion. The reference 



is to the construction of submarine boats in order to sink the Turkish 



galleys in the Gulf of Venice " by smashing the ships in the keel and 



sinking them together with the men in them." Leonardo considers 



this to be justifiable because it is an act of defence " for the safety 



of our Italian lands " (" delli nostre parti italiche ") ; but he will not 



give any details of the construction of his submarine craft, in which 



it would be possible to remain under water for four hours, because 



he is fearful of the evil use to which it might be put in future times. 



With the list of war inventions may be numbered his researches 



in aviation. He pursued this subject for many years. His studies 



range from the consideration of primary causes of flight of birds 



and other winged creatures to the invention of a screw propeller and 



the consideration of its applicability to aerial navigation. He also 



made an actual attempt. Jerome Cardan, the physician who made a 



horoscope for Edward VI., in his work De SuUilitate refers to an 



unsuccessful attempt at flight made by Leonardo da Vinci, and adds 



somewhat drily, " he was a great painter." A sentence on the cover 



of Leonardo's manuscript, Sul Velo degli Uccelli, written in 1505, has 



been interpreted as referring to this attempt. "The great bird," 



it runs, " will take its first flight upon the back of the great swan, 



filling the whole world with amazement, and filling all records with 



its fame ; and it will bring eternal glory to the nest where it was 



born." 



This enigmatic utterance may be somewhat more comprehensible 

 if it is remembered that cecero is the Italian word for swan, and " the 

 back of the great swan " may therefore be interpreted as a reference 

 to Mont Ceceri, a hill to the south-west of Fiesole, from which it is 

 believed the flight took place. 



