Method for Learning

If one wants to view the pieces from another angle, simply turn the varnished paper over and trace it inverted.
Another way to accurately copy an oil painting is to brush over the main lines with oil-ground lacquer and apply a paper of the same size over it; then, passing the hand over, the lacquer lines will adhere and leave the drawing of your piece marked on the paper, which can then be traced as mentioned above. Be careful to remove all remaining lacquer from the painting before it dries using breadcrumbs.

Machine to reduce a drawing without knowing how to draw.

There are even more secure and easier inventions than those we just taught, especially for people who do not know how to draw. The first is through the use of a mathematical compass. This device is usually made of ten wooden pieces in the form of thick rulers, two lines thick, half an inch wide, and one to one and a half feet long, depending on whether you intend to draw larger or smaller pieces. These ten rulers assemble at the top, middle, and bottom, forming diamond shapes. The drawing you want to copy and the paper on which the copy is to be made are attached to a smooth table. The mathematical compass is also planted using a point or thick pin at the end of the first foot, secured firmly so it does not slip and so it allows the device to turn. When you want to copy from large to small, place ...

Translation Notes

• The phrase "compas mathématique" refers to an instrument similar to a pantograph, used to copy and scale drawings.
• "Laque broyée" refers to a ground lacquer used in traditional painting techniques.