28 PETER GUTHRIE TAIT 



swerves to right or left according as the axis of rotation tilts down to the 

 right or to the left. The clue was found, and the rest of the investigation 

 was merely a question of overcoming the mathematical difficulties of the 

 calculation. Thus undoubtedly before his son's brilliant drive of 250 yards' 

 "carry," Tait knew well the influence of the underspin in prolonging both the 

 range and time of flight; and before the summer of 1893 he had calculated 

 the effect of the underspin sufficiently to establish the truth of his theory as 

 a complete explanation of the flight of a golf ball. The results are given in 

 the third article "On the Physics of Golf" (Nature, Vol. XLVIII, June 29, 1893), 

 which is an abridgment of his first paper "On the Path of a Rotating Spherical 

 Projectile" (Trans. R. S. E. Vol. xxxvu, Sci. Pap. Vol. u, p. 356). The 

 theory is stated in popular language in an article on " Long Driving " 

 communicated to the Badminton Magazine (March 1896) and reprinted 

 below with slight additions and alterations made by Tait himself. 



Following up the indications of his theory Tait attempted to improve the 

 driving power of a " cleek " or " iron " by furrowing its face with a number of 

 fine parallel grooves, which by affording a better grip on the ball might be 

 expected to produce a greater amount of underspin. He got several clubs 

 constructed on this principle ; and four form part of the Tait collection 

 of apparatus in Edinburgh University, having been presented to the 

 Natural Philosophy Department by Mrs Tait. One of these is a "universal 

 iron," in which the iron head in addition to being grooved is adjustable 

 to all possible inclinations. The idea was to supply the golfer with one 

 club having a degree of " loft " which could be varied at will. Tait 

 himself found the weapon serviceable enough ; but Freddie would have 

 none of it. 



The elucidation of the golf ball problem led Tait to another line of 

 research, namely, the investigation of the laws of impact. These experiments 

 and their bearing on the manner of projection of the ball are discussed in 

 a later chapter, and in the article on " Long Driving " already referred to. 



Outside his University duties Tail's energies were devoted mainly to the 

 interests of the Royal Society of Edinburgh. Elected a Fellow in 1860 he 

 became one of the Secretaries to the ordinary meetings in 1864, and in 1879 

 succeeded Professor J. H. Balfour as General Secretary. This important post 

 he continued to hold till his last illness. With the exception of his early 

 mathematical papers, his conjoint papers with Andrews and with Balfour 

 Stewart, and a few mathematical notes communicated in later years to the 



