SCIENTIFIC AND LITERARY ACTIVITY 23 



experiments the most striking I could muster professedly without any explanation 



in fact gave them as examples of the objects of Nat. Phil I gave a 20 m. 



lecture on the nature of the study, and the arrangements for the present session, 

 and then plunged into the paradoxes. I reserved as the last the beautiful one of 

 balls and egg shells suspended on a vertical jet of water, as they cannot be shown 

 without some risk of a wetting to the performer and the nearest of the audience. 

 To-morrow I bring into play the large American induction coil, and show the 

 rotation of a stream of violet light in vacuo round a straight electromagnet. I shall 



also show an inch spark in air and the discharge by it about 10 times per second of 



a jar with about 3 square feet of tin foil. There is no self acting break for safety 

 the interruption is made by a toothed wheel worked by hand which for short 

 experiments is much preferable. I shall also show the huge Coin magnet (made 

 under Pliicker's direction) which took six of us to heave it up a gently inclined 

 plane into the class room this afternoon 1 " 



Outside his official University work his tireless energies were finding 

 other fields for exercise. He wrote most of the longer and more important 

 physical articles as well as the article Quaternions for the first edition of 

 Chambers Encyclopaedia (1859-68) edited by Dr Findlater. His friendship 

 with Findlater had important consequences ; for it was he who first took Tait 

 out to learn the game of golf on the Bruntsfield Links, where they played 

 frequently together. 



In 1 86 1 he began the writing of Thomson and Tail's Natural Philosophy, 

 while at the same time he was busy strengthening himself in the use of 

 quaternions and preparing his book on the subject. 



Together with Kelvin he communicated to Good Words in 1862 an 

 article on Energy, which was intended as a corrective to Tyndall's state- 

 ments regarding the historical development of the modern theory of heat. 

 This led to two important articles in the North British Review which finally 

 took shape as his admirable Sketch of Thermodynamics (1868). 



Some curious speculations by Balfour Stewart as to the thermal equi- 

 librium within an enclosure of a number of radiating bodies moving with 

 different velocities led Balfour Stewart and Tait to plan a series of experi- 

 ments on the heating of a disk by rapid rotation in vacuo. The results were 

 communicated to the Royal Society of London ; but no definite conclusion 



1 In these days a roomy platform a few steps above the floor both of the class room 

 and retiring room lay behind the long curving table on which the experiments were arranged. 

 About 1880 the rapidly increasing number of students compelled the addition of two new 

 benches, and this addition was managed by removing the platform, lowering the table and 

 setting it back nearer the wall. The old Natural Philosophy lecture room is now used by 

 the Logic and Psychology departments. 



