On a former occasion I took the liberty of submitting to your inspection in manuscript, some Observations on certain philosophical subjects, and afterwards sent you a printed copy of them. I now do myself the honour to send you a copy of a revised edition, with the addition of other theories, together with corrections and improvements on the first. I have taken the farther liberty to annex to the humble performance the letter which you did me the kindness to write to me; to which is also appended, some Remarks by Dr Mitchill. Should a second perusal enable you to glean from it any thoughts that will compensate you for the trouble, I should deem it a sufficient honour conferred upon me.