Do experiments on the vacuum, by the machine [air pump] and otherwise, and determine the weight of the air.
Examine the force of powder by enclosing a small quantity of it in a box of iron or of very thick copper.
Examine in the same manner the force of water rarefied by fire.
Examine the force and the speed of the wind, and the use one can derive from it for navigation and for machines.
Examine the force of percussion, or the communication of motion in the impact of bodies, of which I believe I have found the true rules.

For example, to know what weight, heat, cold, magnetic attraction light, color are; of what parts air, water, fire, and all other bodies are composed; what purpose is served by respiration in animals; in what way metals, stones, and grasses grow: of all these things one knows little or nothing, yet there is nothing in the world, the knowledge of which would be so desirable or more useful.

One should, according to the diverse matters of which I have just named some, divide up the chapters of this history and bring together in them all the observations and experiments that pertain to each in particular. One should not take trouble to report there so much rare and difficult-to-perform experiments as those which would appear essential for the discovery of what one is seeking, even if they are quite common.

The usefulness of such a history faithfully carried out extends to the whole human race and to all centuries to come, because, besides the profit one can derive from particular experiments for varying applications, the gathering of all of them is always a sure foundation for building up a natural philosophy in which one must necessarily proceed from the knowledge of effects to that of causes.

Chemistry and the dissection of animals are surely necessary to this plan, but the operations of the one and of the other would have to tend always to augment this history by some important article pertinent to the discovery of something one has proposed to oneself, without losing time on many small observations of circumstances of which knowledge leads nowhere, so as not to earn Seneca's reproach to the ancient philosophers: they might perhaps find necessary things if they did not seek superfluous things.

We should begin with the matters one will find prettiest and most useful; one will be able to distribute several at a time to as many people among those who compose the group. They shall make a report each week and lecture on what they have gathered, and thus it will be a regulated occupation, which will undoubtedly bring forth very great fruit.
 
 

1. Find the meridian line and the height of the pole at Paris, which are the bases of all other astronomical measurements.
2. Restore [i.e. remeasure] the fixed stars, in which the entire foundation of astronomy rests.
3. Measure the diameters of the sun and the moon in their diverse distances, which will serve to find new hypotheses for their motion, better than those we have at the moment.
4. Observe the quantity of the refraction of the atmosphere, which it is necessary to know in order to rectify observations of the altitudes of the sun and of the stars.
5. Observe the inequality of the days and establish their equation, which is so necessary for calculating the motion of the moon and for eclipses.
6. Perfect telescopes [lunettes d'approche] and microscopes.
7. Observe refraction in every sort of diaphanous body.
7,1. Observe if light is transported [se communique] from afar in an instant.
8. Observe the diameters of the planets, to determine therefrom the ratio of their sizes among themselves and with regard to the sun.
9. Observe spots on the planets and find their motion about their axis.
10. Observe the motion of the companions of Jupiter and make tables of them.
11. With the aid of these tables, observe here and in other places in the world, such as in Madagascar, the occultation of each of the said companions behind or in front of Jupiter, to find thereby the true longitude of the said places and to rectify [current] maps.
11,1. Observe the declination of the magnet and the change that it undergoes.
12. Send pendulum clocks to sea with the necessary instructions and a person to take care of them, to carry out [pratiquer] the determination of longitudes, which has already succeeded so well in the experiments thus far made.
13. Measure the times and ratios of the fall of heavy bodies in air.
14. Measure the size of the earth. Advise on the means of making geographical charts with greater exactitude than hitherto.
15. Establish once for all the universal measure of sizes [i.e. a universal standard of measure] by means of pendulums, and in consequence [the universal measure] of weight.
16. Find precisely [au juste] the ratio of the weight of metals and of every sort of solid and liquid bodies.
17. Seek [chercher] the weight of the air by means of the vacuum machine, which serves for an infinity of other pretty experiments.
18. Observe the force and speed of the wind.
19. Also the speed and for of running water and their relation to the slope.
19,1 Advise on the best and simplest means of raising water.
20. Examiner the force of gunpowder.
21. Also that of fulminate of mercury [l'or fulminante].
22. Also that of water rarified by fire.
23. Examine the force of percussion or the transfer of motion by impact of bodies, a knowledge of which is most useful in mechanics.
24. Examine the force that a body has to move away from the center in circular motion.