I work to the best of my ability to fulfill my promises, by recasting in its entirety the translation of your excellent works; but I am too aware of my deficiencies to hope to render the copy worthy of the original. Permit me to ask you for a few clarifications as I proceed.

I do not find in the dictionary the word orreries, on page 34; I conjecture that it means cadran (“dial”).

Or the words surf and spray, on page 41, whose meaning I cannot guess, and which stop me short.

Or jostled, on page 47, which troubles me less, however.

Your experiment with the resin smoke to make the electrical atmosphere visible pleases me very much. Have you derived all the advantage from it that you could have? I leave the matter to your judgment.

I would like to know what Dr. —— means by my old theme, and by your Doctrine of the Origin, etc.

Will not the experiments on the cold produced by evaporable substances induce you to conduct some experiments on the heat produced by “deliquescent” substances, that is to say, substances that absorb the humidity of the air and are liquefied by it, such as the fixed alkali of tartar, from which tartar oil is produced through dissolution (per deliquium)? With respect to medical electricity, the experiments of the Abbé Sans (two years ago) did not result in the great successes that he promised. I am enclosing the particulars of another experiment, a rather singular one, which a simple artist is conducting. I gave him a short consultation on this subject, where you will see an uncommon idea that I have had for some time about epilepsy.

I return to your letters on cooling: on page 347, is it quite exact to say that the silkworm is clothed in its silk in its embryonic state? The transformation of the worm into a chrysalis takes place within the silk cocoon, but the true embryonic state is, in my opinion, in the egg before the worm hatches out.

Doesn’t your magic square of eight fail to add up to 260 with its diagonals? I have amused myself by making a magic square that fulfills all your conditions, and meets a few additional difficulties as well, such as letting halves or quarters of the square be transposed, without any damage being done to the pattern. It is a square that always adds up to 11,000 in all directions, in honor of the 11,000 virgins of our legends. In your magic square of sixteen, there is at least one repeated number (241) and at least one faulty line, which is the first line; since I stopped with that very cursory inspection, procured me by chance, I would like you to take another look, to see whether there are not any other faulty lines.

Coals, on page 362, is as far as I can tell what we call charbon de terre, but we consider it a fossil of vegetal origin, not a fossil from the earliest age of our globe, which you should bear in mind.

Have you repeated your attractive experiment on the movement of liquids, using three liquids of different weights and of quite distinct colors, such as guaiacum tree oil, water, and ordinary oil, as I have had the honor of proposing to you?

Would you not find it interesting to try to determine the maximum and minimum proportions of the depth of navigable canals to the boats that they are able to carry?

I have not found in the dictionary the word track-schuyt, on page 492. But that is enough questions at once. If you can accustom yourself to my importunities, they will be followed by many others.

Would you like me to send you a few translated notebooks, before I go any further? By now they could well comprise an eighth part of the whole. I will have at least a few of them delivered to you by Mademoiselle Biheron, if she returns to London toward the end of next month, as she is prepared to do; but I am afraid first because of her health, which is not yet very good, and second because of the expenses of the journey, which will not fail to be great, and from which she may not yet perhaps derive any profit. In God’s name, if you do not foresee any better success from this journey than from the preceding one, be kind enough to tell me so between ourselves, and I would insist on reasons of her health in order to keep her here.

I am also going to look into having the plates which are necessary for the next edition re-engraved; therefore I beg you first to look again at the large magic square, in order to make it absolutely correct, and second to think about whether you would not have some new figures to add to these plates, and to let me know about this without delay. We must see to it that you can take away with you, when our Europe loses you again, a parcel of the complete translation of your works.

As for my Little Code on Reason, I abide by what I had the honor of mentioning to you in my last letter. If you find it too difficult to have it published in French in London, please be so kind as to send it back to me; I will be able to have it published secretly in the provinces.

My wife, and her female neighbors, and all the friends of yours I know, both men and women, have entrusted me with a thousand kind regards for you, without forgetting your worthy friend Mr. Pringle. I have the honor of being, with an inviolable attachment, Monsieur and dear friend, your very humble and very obedient servant