Leonardo da Vinci's aerial screw

Some time ago I received a visit from a servant to the Duke for yet another flying contraption, though this time the model was to portray the idea of a device for a theatre spectacle. Again, within minutes, Salai appeared bearing notebooks under his arm. I had no sooner counted out my Ducats from the Duke than I was reaching into my pockets to pay the rascal for the chance to glean more information from the scribblings of the Florentine master.

As always Leonardo's drawings come with a flair of the artistic. They move off the page, alive and in motion. But I must use my mind to see through the moving parts and capture the static details. I find my confirmation in what small jottings Salai will let me see. From the sketch of the master comes my drawing, thus:

As I see it all moves as one, pivoting on the central column against the stationary slatted base. The base is the platform giving purchase to men who will push the whole in its circular motion by pushing the cross bars, like sailors at a windlass on a ship.

I planned for the model to be 5 feet across. I sketched it out and then set to work with old wood, first making the slatted base, and then the external ring seated beneath it. There are four diagonal support struts and a central column planed down to eight sides. From the column, above the braces, I made square mortices every inch and a half and ran 30 inch rods fanning around for one full circle. At this point I began to reduce their lengths by 2 inches successively until I had completed another half turn.  

The devil in the job was applying the cloth to the framework. The radiating struts support a wire perimeter bound in place by twine. The fabric was applied in sections as large as I could manage to reduce stitching. Even so my fingers became weary plying the thread, and I found myself resorting to a system borrowed from bookbinding using application of glue as often as possible. 

I  also fashioned two little manikins to ride on this merry-go-round as though they were running their little hearts out. I am pleased with them for they have the spirit of da Vinci's drawing. 

As I spin it there's a convincing sense of life, but not even a hint of a downward breath from the swirling sail overhead. I have my doubts that this thing would ever fly in real life. It also strikes me that were it to come off the ground, even for a moment, the slatted base would as willingly spin in the opposite direction to the turn of the upper screw. I think this contraption is better kept for the stage. 

 

Leonardo da Vinci Underwater Apparatus

In these troubled times I keep my head low, but take my orders from whence they come, and am happy to be paid.

Now Cesare Borgia is the man with the orders and the small bag of seven Ducats. Now, instead of a machine that will let us fly I am to contrive a breathing apparatus that will let us swim like a fish. And again, that rascal, Salai, has come with the book of drawings and the price for the time it takes to find the details. And once more the Florentine master is away. I believe they do this to vex me!

The first drawing is little better than a sketch, an idea that more resembles a horse's feed bag and the tentacles of a squid than any design to work from. 

Lost in the margins are some tiny details from which, after yet more coins to Salai, I was able to discern a system of tiny gates to allow a flow of air into the mask through one tube and the expulsion of breath out of the mask through another. 

From this information I was able to make my own sketch and thus get a sense of the requirements to fulfil the obligations of my job. 

At first the task seemed easy enough. I acquired some round discs of glass for the eyes, leather for the job, and from my blacksmith friend the round wire needed to create coils which will line the leather hoses and, in the final use, provide internal support so the hose cannot be crushed by the great weight of water.

Buy my own efforts I was able to turn these coils and create a tapered filler to hold my leather work in place. 

The mask itself was made from a tube of leather onto which I first worked the mouthpiece and the eyeglasses. 

The wire coil was passed through the tube. I hope this is sufficient for I did not endeavoured to sew the leather so tightly to the coil that they cannot be extracted one from the other. 

While this all seemed simple enough I discovered that I was more challenged by the making of the tiny gates fastened to wooden disks. These were secured with thread and beeswax to the wire ring just inside the mouth area. 

The gates were made of leather pieces sewn to a bronze rod which was then fastened by loops to the wood. The attachment allowed for a gentle flap and will, I hope, give sufficient sealing when the inhalation or exhalation of air forces one open and draws the other closed. 

From the outside the mask now looks like this. Tube extensions must be added, sufficient sealing of the seams must be done with some soft beeswax, and prayers must be given for the first person who has to use this!

I  am guessing that the curious sack beneath the mouth piece is to take spittle and leakage from the whole system. Prayers not withstanding, that does not give me hope!

In an attempt to mitigate against leakage I have applied hot bees wax to the joints and seams, and oils and greased the whole. From the upper leather tubing I have added hollow wooden tubes. All is ready for the first mad man who wishes to volunteer. I hope it is Salai, and I hope I have not done my job properly!