LITERARY WORK, ETC. 231 



The lecture which I gave at Davos on the science of the 

 nineteenth century (a subject suggested by Dr. Lunn) led me 

 to think that an instructive and popular book might be made 

 of the subject, as I found there were so many interesting 

 points I could not treat adequately or even refer to in a 

 lecture. I therefore devoted most of my spare time during 

 the next year to getting together materials and writing the 

 volume, which I finished in the spring of 1898, and it was 

 published in June. The work had a pretty good sale, and at 

 the request of my publishers I prepared from it a School 

 Reader, with a considerable number of illustrations, which 

 was published in 1901. This suggested the idea of a much 

 enlarged and illustrated edition of the original work, which 

 was, as regards many of the more important sciences and 

 arts, a mere outline sketch. Almost all the year 1902 and 

 part of 1903 was occupied in getting together materials for 

 this new work, as it really was, and it was not published till 

 the autumn of the latter year. 



Since my general health has improved, however, they have so much 

 diminished as no longer to give me much trouble. I have also suffered 

 twice from severe eye troubles. My sight has always been myopic, 

 though otherwise strong, but in 1883 I did a great deal of work at night, 

 requiring a continual reference to several books of different sized 

 print, and this brought on rather severe inflammation of the retina, 

 which necessitated a darkened room for some weeks, and no reading 

 or writing for several months — a tremendous trial to me, so that I 

 was able to do no literary work in 1884. The oculist I consulted told 

 me that with care in two or three years my eyes would be as strong 

 as ever; and they very gradually became so, and I had no further 

 trouble till 1891, when some irritating substance got into my left eye 

 and could not be got out, causing severe inflammation for some weeks, 

 which, however, passed away without immediate bad results. From 

 that time, however, there began a loss of the power of adjustment of 

 the two eyes, so that I saw distant objects double, and this has 

 increased so that I now see everything double, even at the other side 

 of a room; but this does not much inconvenience me, except to pro- 

 duce a general indistinctness of objects. Two persons walking together 

 on the other side of the street seem to me to be three or four persons, 

 according to the angle of sight, and I often have to shut one eye in 

 order to be sure how many there are. The divergence has now, I think, 

 got to the worst, as I perceive no difference during the last few years. 



