In his letter to his college classmates in 1897 he says that he has “well in hand a work on electricity, and one on homiletics prepared when teaching theology.” Neither of these was finished and published. To his college classmate, S. C. T. Dodd, Esq., he wrote in 1898 that he was trying also to finish a work on moral philosophy. In March, 1878, he wrote to Dr. W. A. P. Martin, of Peking: “You will remember probably that when you were here I spoke of my intention to make a natural philosophy by and by. You said, ‘Go ahead,’ and that you would retire in my favor by the time mine was ready, say, ten years hence. If I am spared I hope to have the book ready within the time, if not sooner. As you know, natural philosophy is my hobby, and I have taught it more thoroughly probably than has been done in any other school in China. I intend when I visit America to prepare myself with the material and the facilities for such work.” He was not able to find time for this work; and when later Dr. Martin invited him to write for the revised edition of his treatise the chapter on electricity, this privilege had for the same reason to be put aside. He had also advanced far toward the completion of a translation of “Pilgrim’s Progress” into Mandarin. His “Mandarin Lessons” was published early in 1892, and immediately commanded a success even larger than its author may have anticipated. Ever since, it has gone on toward a more general use by foreigners wishing to master the language, and has now far outstripped every other work of its kind. He was a quarter of a century in making the book. June 28, 1873, he made the following entry in his Journal concerning it: Most of last week and this I have spent in making lessons and planning a much larger number than I have made. Mr. Mills urged me to work at them for Dr. ⸺’s benefit, as he did not seem to take hold of Wade. I did not think of what a job I was sliding into when I made three lessons for Maggie a few years ago. I have now laid out quite an extensive plan, and if I am spared I trust I shall be able to finish it, though it will take a deal of work. I believe that I can produce a far better book than any that has yet been brought forth. I was not intending to do this work now, and cannot work much more at it, as other matters imperatively demand attention.