I inclose you part of a letter lately recieved from Dr. Wistar on the subject of certain bones in the possession of a mr Irvill of Cincinnati; & supposed to be those of the Mammoth & Megalonyx. they were formerly destined for Philadelphia, & had got to Pittsburg where the owner beginning to doubt whether they would sell there so as to quit cost, sold them to mr Irvill. it is certainly desirable that we should be able to get those of the Megalonyx, & there being already a compleat skeleton of that at Madrid it is not probable that the sending them to Europe would prove of much profit. if these be any bones of the head of the Mammoth which we do not possess, it would be desireable to get them also; but I am not able to say which of them we have or want. add to this that we are poor, & therefore can give but a moderate price. in this state of uncertainty, the acceptable service which you could render us would be to see mr Irvill and the bones, to observe which of them are probably among our desiderata, & sound mr Irvill so far as to see whereabouts he would be as to price, and to communicate this by letter. we could then decide on a consideration of the objects & our means of acquiring them. in asking you to take this trouble I can only appeal to that zeal for the promotion of science which every man possessing it feels. I communicated to the Society your interesting paper on the Saltpetre caves & rocks. the latter object was entirely new to me. I salute you with friendship & assure you of my great respect