The explanations are admirably clear, and the arrangement appears to be a very good one. No teacher of the high classes in our schools or of students preparing for the university examinations should be without this book. There is nothing like it in English, and it forms an excellent introduction to the various applications of Algebra to the higher analysis. The last few years of Chrystal's life were devoted to a different research topic from anything he had studied up to that point. In February 1903 he was asked to give a brief account of the hydrodynamical principles of seiches, with suggestions to surveyors regarding the observations they might make on Scottish lakes in the Scottish Lake Survey.
Seiches are oscillations in the water level occurring in lakes and along sea coasts.
In these and subsequent papers Chrystal studied seiches in lakes of many different shapes. He also revived his interest in carrying out experiments and in 1905 he organised an investigation of the seiches of Loch Earn, also making observations for comparison on Lochs Tay and Lubnaig. He supervised the whole of the work and designed special instruments to carry out the measurements. Recognition for his work on seiches came through the Gunning Victoria Award made to him by the Royal Society of Edinburgh, one of the most prestigious awards of the Society, and the Royal Medal by the Royal Society of London, confirmation of which came from the King just two hours after his death. It is interesting to look at some descriptions of Chrystal's character.