ORDINARY CLASS LECTURES 19 



to the thermo-dynamic discoveries of Kelvin. His passage at arms with 

 Herbert Spencer Tail himself never regarded as anything else than a 

 big joke. 



As a lecturer Tail was probably unsurpassed by any of his con- 

 temporaries. His lecture notes were merely jottings of headings with the 

 experiments indicated and important numerical values interspersed. In the 

 original note book, which was in use till 1881, these headings were entered 

 with intervening spaces so as to allow for additions as time went on. 

 In 1 88 1 he rewrote the greater part of the notes in a smaller octavo 

 book, and this he continued to use to the end. 



These lecture notes had to do with the properties of matter, which 

 largely occupied the attention of the class for the first half of the winter 

 session. Tait regarded this part of the course as a general introduction 

 to the study of Natural Philosophy. He devoted the first few days to a 

 discussion of the nature of the subject and of the means by which we gain 

 knowledge of the physical universe. His treatment of the subjective and 

 objective from the point of view of the natural philosopher was always clear 

 and reasonable. I remember going back with a former classmate to hear 

 Tail's opening lecture. Since we had first sat together in the benches of 

 the Natural Philosophy Class room my friend had pondered deeply on meta- 

 physical themes ; and, as we listened again to Tail's exposition of objective 

 and subjective, he whispered lo me " Beauliful, Berkeley couldn't have done 

 it better. " 



The conceplions of lime and space, and the realities known as matter 

 and energy, were introduced and placed in their righl selling from ihe 

 physical slandpoint. These preliminaries disposed of, Tait began his syste- 

 malic leclures on the properties of malter. His aim was to build a truly 

 philosophical body of connected irulhs upon the familiar experiences of the 

 race. In ordered sequence ihe various obvious properties of matter were 

 considered, first, in themselves, then in their theorelical setting and their 

 practical applications. Thus, lo take but one example, the discussion of the 

 divisibility of matter led to the consideration of mechanical sub-division and of 

 the elementary principles of the diffraction and inlerference of light, illustrated 

 by colours of soap films, halos and supernumerary rainbows. The fuller 

 explanation of these was, however, reserved for a later date when the laws 

 of physical optics were taken up in more detail. In this way the intelligent 

 studenl was able during the firsl iwo monihs lo gain a general outlook upon 



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