A thousand pardons, my dear and illustrious doctor, if you did not have this note on the condensation of air this morning.

Mr. Boyle has found the way to make air 13 times more dense by compressing it; others claim to have reduced it to th of its volume. Mr. Hales made it 38 times more dense with the help of a press, but by freezing some water in a large ball of iron, he has reduced the air to a volume 1828 times smaller.

However, Mr. Halley claims in the Philosophical Transactions, as a result of experiments conducted in London and others conducted in the former Del Cimento Academy, that one can, in all confidence, determine that there is no force capable of reducing air to an 800th of its volume at the surface of the earth. However, M. Amontons from our Academy holds that there are no limits to the condensation of air and that these limits are only those of our means.

On this note, it should be observed that M. Halley being prior to M. Hales by a number of years and that the latter knowing the experiments and writings of the former, he would not have advanced what he advanced if he had not observed it in his experiments, as he is a very exact man.

That was, my illustrious doctor, an excerpt of the best I could find in the Dictionary of Physics, which took the substance from that of Musschenbroek.

I would propose a game of chess if I weren't waiting for a lady who is coming to see some electrical experiments, but I know that she will leave about eight o'clock. If that hour is not inconvenient, I am at your service.

I was writing you this yesterday, my illustrious doctor, precisely when this lady arrived. I could not send my servant and because of some really singular hitches that I encountered in my experiments, she stayed until nine o'clock. I was afraid you were already asleep.

I am returning Le Mercure.