Your favor of Sep. 28. came to hand a few days ago. I thank you for the details on the Southern and Western lines. There remains thereon one article however which I will still beg you to inform me of, viz. how far is the Western boundary beyond the Meridian of Pittsburgh? This is necessary to enable me to trace that boundary in my map. I shall be much gratified also with a communication of your observations on the curiosities of the Western country. It will not be difficult to induce me to give up the theory of the growth of shells without their being the nidus of animals. It’s only an idea, and not an opinion with me. In the Notes with which I trouble you I had observed that there were three opinions as to the origin of these shells. 1. That they have been deposited even in the highest mountains by a universal deluge. 2. That they with all the calcareous stones and earths are animal remains. 3. That they grow or shoot as chrystals do. I find that I could swallow the last opinion sooner than either of the others; but I have not yet swallowed it. Another opinion might have been added, that some throw of nature has forced up parts which had been the bed of the ocean. But have we any better proof of such an effort of nature than of her shooting a lapidific juice into the form of a shell? No such convulsion has taken place in our time, nor within the annals of history; nor is the distance greater between the shooting of the lapidific juice into the form of a chrystal or a diamond which we see, and into the form of a shell which we do not see, than between the forcing Volcanic matter a little above the surface where it is in fusion, which we see, and the forcing the bed of the sea fifteen thousand feet above the ordinary surface of the earth, which we do not see. It is not possible to believe any of these hypotheses; and if we lean towards any of them it should be only till some other is produced more analogous to the known operations of nature. In a letter to Mr. Hopkinson I mentioned to him that the Abbé Rochon, who discovered the double refracting power in some of the natural chrystals, had lately made a telescope with the metal called Platina, which while it is susceptible of as perfect a polish as the metal heretofore used for the specula of telescopes, is inattackable by rust as gold and silver are. There is a person here who has hit on a new method of engraving. He gives you an ink of his composition. Write on copper plates any thing which you would wish to take several copies; and in an hour the plate will be ready to strike them off. So of plans, engravings &c. This art will be amusing to individuals if he should make it known. I send you herewith the Nautical almanacs for 1786. 1787. 1788. 1789. 1790. which are as late as they are published. You ask how you may reimburse the expence of these trifles? I answer, by accepting of them, as the procuring you a gratification is a higher one to me than money. We have had nothing curious published lately. I do not know whether you are fond of chemical reading. There are some things in this science worth reading. I will send them to you if you wish it. My daughter is well and joins me in respects to Mrs. Rittenhouse and the young ladies. After asking when we are to have the lunarium? I will close with assurances of the sincere1