184 PETER GUTHRIE TAIT 



and leave Balance and Screws and Atwood's Machines, etc., for the small book 

 I mean in the -Second Division of the Book Abstract Dynamics.... 



These extracts together with the letters which have been published in 

 Prof. Sylvanus Thompson's Life of Lord Kelvin (Vol. I, pp. 453-464), show 

 that the final plan of the book must have been agreed upon late in 1862 or 

 early in 1863. Tait had already written a first draft of large parts of the 

 book ; but Thomson could not be got to apply himself steadily to the task. 

 Like a sleuth-hound Tait was always on his colleague's tracks begging for 

 copy or for proofs. When in May 1864 Thomson visited Creuznach for the 

 sake of his wife's health, he received the following letter, whose immediate 

 purpose was to bring him to his desk and pen. 



6 G. G. E. 



20/5/64. 

 Dear T., 



Send something for $. I have only written the examples twice yet, and 

 the Kinetics of a particle but once.... 



Rather a curious thing to-day. Thunderstorm. Divided-ring (very low charge) 

 going, and discharging every two minutes, when a thunder-cloud was close, by a 

 spark from a fine wire i mm. from the electrode. Abscissae G. M. T. (as supplied 

 by Her M. A. Royal for Scotland). Ordinates potential at class-room window 

 I inch = 500 zinc-copper pairs. 



ih 1m 2m 



Note the effect of the gun 1 ist on cloud north of the Coll.; then (after more 

 than 30 s.) on one to the south.... 



When you ARE at Xnach, I hope you won't spend ALL your time with 

 Dellmann, but will devote at least 4 h. per day to Kinetics of Rigid (about point) 

 and Elastic Bodies (including Fluids). If you do, we can easily appear in August, 

 and have the S. B. [ = small book] ready for November. 



I send you a proof of my Energy 2 signed for press the publishers want me to 

 make a little volume of it and its predecessor (with mathematical developments). 

 I said I would be guided by you and E. They said Engineers had urged them to 

 get it done. Ponder O. T. and C. E. on this, as well as on other subjects'. 



1 The Edinburgh Time Gun is fired every day, except Sunday, at i p.m. Greenwich 

 Mean Time. 



* One of the articles in the North British Review, which finally became the second 

 chapter of Tail's Sketch of Thermodynamics. 



8 The initials are difficult of interpretation. They may refer to Rankine the well-known 

 Professor of Civil Engineering in Glasgow University. Possibly C.E. means see Engineers. 



