ADVANCED CLASS LECTURES 21 



in mathematics, studied the first three sections of Newton's Principia. This 

 home work was however purely voluntary even when, under the later 

 regulations, the attendance of students at the examinations on the Class 

 Lectures became compulsory. 



To the advanced student able to follow him Tait was not merely a superb 

 lecturer but was also a great natural philosopher and mathematician. The 

 more abstruse the subject the more clearly did Tait seem to expound it. 

 The listener felt that here was a master who could open the secrets of the 

 universe to him. Unfortunately, when deprived of the aid of Tail's lucid 

 exposition, in the easiest of English speech, of the knottiest mathematical 

 or physical problems, the student, now left to himself, felt that his original 

 ignorance was doubled. 



In the Advanced Class Tait treated dynamical science in the manner of 

 " Thomson and Tait." He does not seem to have kept notes of his course, but 

 simply to have prepared his ideas the night before the lecture. In the earlier 

 days down to about 1876 he used as a guide the elementary treatise known as 

 " Little T and TV Following the sequence of ideas there set down he 

 developed the subject by use of the calculus. After 1876 he used for lecture 

 notes a set neatly written out by his assistant, now Professor Scott Lang of 

 St Andrews ; but later he found his Britannica article on Mechanics with 

 interleaved blank sheets more suitable for his purpose. In the end he 

 lectured along the lines of his own book on Dynamics, which was largely 

 a reprint of the Mechanics article with important additions on Elasticity and 

 Hydrodynamics. 



One outstanding feature of Tail's style of lecturing was its calm, 

 steady, emphatic strength. He never seemed to hurry; and yet the ground 

 covered was enormous. Was he for example establishing the general equations 

 of hydrodynamics ? Bit by bit the expressions were formed, each added item 

 being introduced and fitted on with the clearest of explanations, until by a 

 process almost crystalline in its beauty the whole formula stood displayed. 

 All was accomplished with the minimum of chalk, but with sufficient slowness 

 to allow of the student adding the running commentary to his copy of the 

 formulae. The equations only and their necessary transformations were put 

 on the black board, the student being credited with sufficient alertness of mind 

 and agility of hand to supply enough of the explanation to make his notes 

 remain intelligible to himself. 



Though broadly the same, his advanced course varied in detail from year 



