The collection consists almost entirely of incoming correspondence, the bulk being 32 letters from his mother and 128 letters from a woman named Melba M. Weber, plus a few others from acquaintances and family, and from physicians and hospitals concerning employment and medical issues. Also, a miscellany of items such as receipts for association dues, an unidentified poem, a tiny baby photo, and three letters relating to his Indian studies. Unfortunately, the collection does not reflect his involvement in Indian linguistics or book collecting, but is chiefly concerned with Siebert’s relationship (or lack of it) over a fifteen-year period with Melba Weber.