During his first Florentine period, prior to 1481, Leonardo drew up a great number of studies and technological projects on folios that have been collected mainly in the Codex Atlanticus, as well as the Codex Arundel and the collection of the Cabinet and Prints and Drawings at the Uffizi.
These studies show remarkable evolution in the graphic aspect and methodology as compared to those of the Renaissance engineers who preceded him in Florence and Siena, from Brunelleschi to Francesco di Giorgio Martini, in addition to Taccola. Moreover, references to Graeco-Roman scientific treatises (from Hero of Alexandria to Archimedes) are evident. We need only think of his manner of demonstrating the assembly and disassembly of the various elements that make up a machine, for example a winch, in a sort of mechanical alphabet or anatomy.
On folios dating from around 1478-1480 we find technological projects concerning methods for walking on water and breathing under water, hygrometers and extraordinary hydraulic devices, self-propelled carts and other automated devices, studies for human flight and for the typographical machine, a great oil press and a roasting spit turned by hot air, furnaces for smelting metals and for distilling, burning mirrors, modular beams and construction site machines. Remarkable are the artistic applications, ranging from the perspectograph to the pantograph, to the projector for "large figures".
For all of this, Leonardo has also been called the artist of machines (Paolo Galluzzi), or the artist of ingenious devices.
When, presumably in 1482, Leonardo, about to leave Florence, had a letter of presentation to Ludovico il Moro compiled by a friend of his who was a scribe, he claimed and demonstrated - at least theoretically - formidable technical knowledge, ranging from the military arts to architecture.
We can read this letter in the Codex Atlanticus:
«Most illustrious Lord, having now sufficiently considered the specimens of all those who proclaim themselves skilled contrivers of instruments of war, and that the invention and operation of the said instruments are nothing different to those in common use: I shall endeavour, without prejudice to any one else, to explain myself to your Excellency showing your Lordship my secrets, and then offering them to your best pleasure and approbation to work with effect at opportune moments as well as all those things which, in part, shall be briefly noted below (and many more, according to the needs of the different cases, etc.).
1. I have a sort of extremely light and strong bridges, adapted to be most easily carried, and with them you may pursue, and at any time flee from the enemy; and others, secure and indestructible by fire and battle, easy and convenient to lift and place. Also methods of burning and destroying those of the enemy.
2. I know how, when a place is besieged, to take the water out of the trenches, and make endless variety of bridges, and covered ways and ladders, and other machines pertaining to such expeditions.
3. Item. If, by reason of the height of the banks, or the strength of the place and its position, it is impossible, when besieging a place, to avail oneself of the plan of bombardment, I have methods for destroying every rock or other fortress, even if it were founded on a rock, &c.
4. Again I have kinds of mortars; most convenient and easy to carry; and with these can fling small stones almost resembling a storm; and with the smoke of these causing great terror to the enemy, to his great detriment and confusion.
5. Item. I have means by secret and tortuous mines and ways, made without noise to reach a designated [spot], even if it were needed to pass under a trench or a river.
6. Item. I will make covered chariots, safe and unattackable which, entering among the enemy with their artillery, there is no body of men so great but they would break them. And behind these, infantry could follow quite unhurt and without any hindrance.
7. Item. In case of need I will make big guns, mortars and light ordnance of fine and useful forms, out of the common type.
8. Where the operation of bombardment should fail, I would contrive catapults, mangonels, trabocchi and other machines of marvellous efficacy and not in common use. And in short, according to the variety of cases, I can contrive various and endless means of offence and defence.
9. And when the fight should be at sea I have kinds of many machines most efficient for offence and defence; and vessels which will resist the attack of the largest guns and powder and fumes.
10. In time of peace I believe I can give perfect satisfaction and to the equal of any other in architecture and the composition of buildings public and private; and in guiding water from one place to another.
Item: I can carry out sculpture in marble, bronze or clay, and also in painting whatever may be done, and as well as any other, be he whom he may.
Again, the bronze horse may be taken in hand, which is to be to the immortal glory and eternal honour of the prince your father of happy memory, and of the illustrious house of Sforza.
And if any one of the above-named things seem to any one to be impossible or not feasible, I am most ready to make the experiment in your park, or in whatever place may please your Excellency—to whom I commend myself with the utmost humility &c. »
Interest in technological studies, science, mathematics, the alphabet of the waters and the anatomy of the human body, were at the centre of Leonardo's studies in his second Florentine period as well. Not all of the work done in these years has survived; in his writings, in fact, Leonardo often mentions treatises remained unfinished or that have now been lost.
On April 3, 1501 Fra Pietro da Novellara wrote to Isabella d’Este, stating that Leonardo «is working hard on geometry, and most impatient of his brush».
Of all of the machines drawn on the folios during his Florentine period, few can be traced to precise locations. Undoubtedly linked to Florence were the models of sandbanks in the Arno mentioned in the Codex Leicester, perhaps an anatomical model, and obviously the mobile scaffolding used to fresco the Battle of Anghiari in Palazzo Vecchio. Fabricated in France but sent to Bernardo Rucellai, a Florentine nobleman, was instead the water meter, a system for calculating the amount of water consumed or the amount sold.