Another Michelangelo's Sketch for stone masons to cut the marble for the statue
"The two blocks of marble to be shipped to Micelangelo from Carrara are firmly identified in this pen sketch which records his ownership. Not only has he noted the shape and measurements of each block, but he also shows the postion of his mark, three interlocking circles, in which have been added the initials of the stonecutters themselves.
A note at top, in his handwriting, identifies th men by name. And as a further guarantee that these blocks were indeed his, Michelangelo had this sketch and several others like it notarized by a solicitor at Carrara."
Frist Wax sketch or sketch for carvers for River god.
Ludwig Goldscheider, says"For each full-scale model which Michelangelo made there were at least two small models. The first was only a slight sketch, which, combined with drawings showing the measurements of the planned sculpture, served as a guide to determine the right size of the marble block to be used for the work. 'On the 9th of April, 1521,' we read in a Ricordo by Michelangelo, 'I received from Cardinal Medici a letter, and from him through Domenico Buonsegni 200 ducats, in order that I should go to Carrara and make there contracts for the quarrying of marble blocks for the Medici tombs which are to be erected in the Sagrestia Nuova of San Lorenzo. I went to Carrara and remained there for 20 days, taking measurements in clay [i.e. clay models] and drawing them on paper.'".